2. Phonology

2.1. Classification of Sounds

2.1.1. The vowels are short [a], [e], [i], [o], [u], written a, e, i, o, u, and long [], [], [], [], [],written ā, ē, ī, ō, ū, respectively. The other sounds are consonants.

The Indo-European diphthongs proper are [ei̯], [oi̯], [ai̯], written ei, oi, ai, and [eu̯], [ou̯], [au̯], written eu, ou, au. Both vowel sounds are heard, one following the other in the same syllable.

NOTE. For the so-called long diphthongs [i̯], [i̯], [i̯], written ēi, ōi, āi, and [u̯], [u̯], [u̯], written ēu, ōu, āu, which remained only in Indo-Iranian, Greek and partly in Baltic languages, Schulze (1885) interpreted a regular correspondence of the type āi/ā/ī, which came respectively from the full grade of the long diphthong, the full grade before consonant (where the second element was lost), and the zero-grade (a contraction of schwa with the semivowel). Martinet (1953) proposed that laryngeals were behind those long diphthongs.

In any case, in the languages in which they are retained, long diphthongs have not a longer duration than normal diphthongs; phonologically they are equivalent, as Vedic and Greek metric shows. Adrados–Bernabé–Mendoza (1995-1998): “[t]he difference, therefore, is not the duration of the group, but the relative duration of their components; in other words, e.g. ei and ēi have the same phonological duration (they are long, as opposed to a brief vowel), but in ei both elements have approximately the same duration, whereas in ēi the duration of i is perceptibly shorter than e. Because of that, the name ‘long first-element diphthongs’ is more appropriate to refer to these phonemes.” Cf. Allen (“Long and short diphthongs”, in Morpurgo Davies and Meid (eds.), 1976) for an analysis of these diphthongs.

Strictly speaking, phoneticians do not consider the so-called rising diphthongs, [je], [jo], [ja], [j], [j], [j], nor [we], [wo], [wa], [w], [w], [w], as diphthongs proper, but rather sequences of glide and vowel.

The formations usually called triphthongs are [jei̯], [joi̯], [jai̯], [jeu̯], [jou̯], [jau̯], as well as [wei̯], [woi̯], [wai̯], [weu̯], [wou̯], [wau̯]; and none can be strictly named triphthong, since they are formed by a consonantal sound [j] or [w] followed by a diphthong. The rest of possible formations are made up of a diphthong and a vowel.

NOTE. Whilst most Indo-Europeanists differentiate between sequences of approximant and vowel (rising diphthongs) from true falling diphthongs in their transcriptions, i.e. writing [je] (from [i]+[e]) but [ei] or [ei̯] (from [e]+[i]), some use a different approach, considering all of them combinations of vowel plus glide or glide plus vowel, i.e. writing [je] and [ej], or [i̯e] and [ei̯].

2.1.2. Consonants are either voiced (sonant) or voiceless (surd). Voiced consonants are pronounced with vocal cords vibration, as opposed to voiceless consonants, where the vocal cords are relaxed.

a. The voiced consonants are [b], [d], [g], [gw], [l], [r] and [ɾ], [m], [n], [z], [j], [w].

b. The voiceless consonants are [p], [t], [k], [kw], [s].

c. The digraphs bh [bh], dh [dh], gh [gh] and ch [gwh] represent the Indo-European voiced aspirates proper whereas th [th], kh [kh], represent voiceless aspirates.

NOTE. Although written as digraphs, each aspirate is considered a single consonant, not a combination of ‘consonant plus aspiration’. The same is valid for labiovelars.

d. The resonants [r], [l], [m], [n], and the semivowels [j] and [w], can function both as consonants and vowels, i.e. they can serve as syllabic border or centre.

NOTE. There is a clear difference between the vocalic allophones of the semivowels and those of the resonants, though: the first, [i] and [u], are very stable as syllabic centre, whereas the resonants ([r̥], [l̥], [m̥], [n̥]) aren’t, as they cannot be pronounced more open. Because of that, more dialectal differences are found in their evolution.

2.1.3. The mutes are classified as follows:





















Labialised velars or Labiovelars q [kw], c [gw], ch [gwh], are pronounced like [k], [g], [gh] respectively, but with rounded lips.

NOTE 1. Labiovelar stops are neutralised adjacent w, u or ū; as in Gk. bou-kólos ‘cowherd’, from *gwou-kolos, dissimilated from *gwou-kwolos (which would have given Gk. *bou-pólos), cf. Gk. ai-pólos ‘goatherd’<*ai(g)-kwolos (Fortson 2004). This is related to the question of the actual existence of the groups [kw], [gw], and [ghw], different from (and similar or identical in their dialectal outputs to) labialised [kw], [gw], and [gwh]. A distinction between both is often found, though; as, kwōn, dog, ekwos, horse, ghwer-, wild,  kweidos, white, kwet-, cook (cf. O.Ind. kwathati), tekw-, run, etc. For a defence of such unified forms, see e.g. Halla-aho <http://ethesis.helsinki.fi/julkaisut/hum/slavi/vk/halla-aho/problems.pdf>.

NOTE 2. German Neogrammarians reconstructed a fourth series of phonemes, the voiceless aspirates *ph, *th, *kh, to explain some irregularities in the outputs of the voiceless row. Most Indo-Europeanists reject this fourth independent row of phonemes, and findings of Indo-Iranian, Armenian and Greek have been explained as 1) expressive in origin, 2) contact of a voiceless with a laryngeal phoneme, and 3) effect of a prior s. For support of the fourth row, see e.g. Szemerényi (1985).

2.1.4. The so-called liquids are l, which represents the alveolar lateral approximant [l], and r, pronounced in PIE and (at least occasionally) in most modern IE languages as alveolar trill [r], today often allophonic with an alveolar tap [ɾ], particularly in unstressed positions. These sounds are voiced.

NOTE. Cf. Ban’czerowski (“indoeuropäisches r und l, LPosn. 12/13, 1968).

2.1.5. The nasals are labial [m], written m, and dental [n], written n. These are voiced. The velar nasal [ŋ] – as ng in English sing – could have existed in IE as allophone of [n] before velars.

NOTE. Erhart (Studien zur indoeuropäischen Morphologie, 1970) reconstructs three nasals, *N, *M1 and *M2, this one a fricative seminasal with which he explains the results of alternating m and w in some suffixes and roots; as, -ment-/-went-, men-/wen-, etc. He left unexplained, though, under which conditions they would have changed.

2.1.6. The fricatives are voiceless [s] and voiced [z], with z being usually the output of s before voiced consonants.

NOTE. [z] was already heard in Late Indo-European, as a different pronunciation (allophone) of [s] before voiced stops, as can be clearly seen in LIE nisdos [nizdos] nest, which comes from PIE roots ni-, down, and zero-grade -sd- of sed-, sit.

2.1.7. The semivowels are usually written j, and w. These are voiced.

NOTE. Some authors make a distinction between consonantal [j], [w], and vocalic [i], [u]. Actually, however, both appear as CIC and VJV, and never as CJC or VIV (and the same is valid for resonants and their vocalic allophones).

2.1.8. Gemination appears in phonemes whose duration is long enough to be perceived – their implosion and explosion, both audible – as distributed in two syllables. They existed in LIE: in stops, as appās, attās (and tātā), dad, pappājō, eat, or kakkājō, shit; in nasals, as annā, ammā (andmammā), mother, mum; in liquids, as bōullā, buble; and in the sibilant, as kussō, kiss.

NOTE. They appear mostly in words of expressive origin, children vocabulary, onomatopoeia, etc., which makes it more likely that PIE inherited gemination mainly as an expressive resource, different from its central phonological system; a resource that was retained for a long time by most IE languages as a recurrent possibility.

2.1.10. A synoptic table of the Indo-European phonetic system:































































l, r












NOTE. The glottal stop ʔ is the remain of the unified Late Indo-European laryngeal *H (v.s. The Loss of Laryngeals). Its effect was usually a lengthening of the preceding vowel, although remains might be found in some ancient lexica and frozen expressions, especially accompanying sonorants. It is not usually written in this book, though; cf. ga-, written with a late West IE output gnātó- for practical reasons; see §5.5.2 for writing conventions in numerals. Examples of its actual pronunciation are found today in Germanic; cf. American Eng. cat [khæʔ(t)], BBC Eng. button [b̥ɐʔn̩], Ger. (northern dialects) Beamter [bəˈʔamtɐ], (western dialects) Verwaltung [ˌfɔʔˈvaltʊŋ], Du. beamen [bəʔamən], or Danish hand [hɞnʔ].

2.2. Pronunciation

2.2.1 The following pronunciation scheme is substantially that used by Indo-European speakers at the end of the common Late Indo-European period.

2.2.2. Indo-European vowels and examples in English and French:
















made (esp. Welsh)

été (but longer)













note  (esp. Welsh)













NOTE. Following the mainstream laryngeal theory, Proto-Indo-Hittite knew only two vowels, *e and *o, while the other commonly reconstructed vowels were earlier combinations with laryngeals. Thus, short vowels a < *h2e; e < *(h1)e; o < *h3e, *(h1)o; long vowels ā < *eh2; ē < *eh1; ō < *eh3, *oh. Different schools consider a or o to be the output of *h2o in Late Indo-European. Short and long vowels , are variants of the semivowels j and w.

2.2.3. Falling diphthongs and equivalents in English and French:

i  as in Eng. vein, Fr. Marseille

u  Eng. e (met) + u (put), Fr. Séoul

i  as in Eng. oil, Fr. coyotes

u  as in Eng. know, Fr. au + ou

i  as in Eng. Cairo, Fr. travail

u  as in Eng. out, Fr. caoutchouc

NOTE. In long diphthongs, the first component is pronounced longer than the second one, but the duration of the group is the same (see above).

2.2.4. Consonants:

1. b, d, h, l, m, n, are pronounced as in English.

2. p, k, t, are plain as in Romance, Balto-Slavic, Greek or Indo-Iranian languages, and unlike their English or German equivalents, cf. Fr. pôle vs. Eng. pain, Fr. qui vs. Eng. key, Fr. tous vs. Eng. tongue.

NOTE. The aspirate or ‘h-sound’ which follows the English k disappears when the k is preceded by an s, as in skill.

3. t and d are made by striking the edge of the teeth with the tip of the tongue, as in Romance languages, and unlike English, in which it is made with the tongue drawn a little further back, so that the tip strikes against the front of the palate or the teethridge. In other words, the place of articulation is the same as for the English th en thin.

4. g always as in get.

NOTE. For Balto-Slavic palatalisation, compare the g in garlic and gear, whispering the two words, and note how before e and i the g is sounded farther forward in the mouth (more ‘palatal’) than before a or o. That is what we represent as [gj] when writing a palatalised g. Similarly, we use [kj] pronounced as k in key compared to c in cold.

5. c stands for [gw], which is pronounced similar to [g] but with rounded lips. Compare the initial consonant in good with get to feel the different articulation. The voiceless q (which stands for [kw]) is similar to [k] but pronounced with rounded lips; as c in cool, compared to c in car.

6. The voiceless aspirated kh, th, are pronounced very nearly like English word-initial p, k, t, as in pen, ten, Ken, but much more aspirated. The extra aspiration might be trained by using English words with combinations of p+h, t+h, k+h, i.e. to the corresponding mutes with a following breath, as in loop-hole, hot-house, block-house, pronouncing them first in two distinct parts and then more rapidly, trying to run the p, k, t, on to the following syllable.

7. The aspiration of voiced bh, dh, gh, ch, must be a voiced aspiration, which makes their pronunciation troublesome.

NOTE. “The key to the pronunciation of all these letters is learning to pronounce a voiced h instead of the voiceless English h (it is true that some English speakers make voiced h a rather infrequent allophone of h – e.g. in the word inherent). Voiced sounds are those made with a vibration of the vocal cords. Some consonants are voiced, others voiceless. All vowels are voiced, unless you whisper them. An extremely easy way to tell whether a sound is voiced or not is to put your hands firmly over your ears: start by making a prolonged sss sound, which is voiceless; then make a zzz sound, which is voiced, and you will hear the vibration of the vocal cords very plainly as a droning in your ears. Lengthen the ordinary English h into a prolonged breathing and it will be quite obviously voiceless. The task now is to modify this breathing until you can hear that it is accompanied by the droning. The sound you are aiming at is similar to the sound children sometimes use when they want to make someone jump. The voiced h, once produced, can easily be combined with g, b, etc., and practice will soon smooth the sound down until you do not seem to be trying to give your listeners a series of heart attacks.” Coulson (2003).

8. j as the sound of y in yes (probably more lightly), never the common English [d͡ʒ], as j in join; w as in will.

9. Indo-European r was probably slightly trilled with the tip of the tongue (still common today in many IE languages), as in Scottish English curd. In the majority of IE languages, and thus possibly in PIE, this sound is at least occasionally allophonic with an alveolar tap [ɾ], pronounced like the intervocalic t or d in American or Australian English, as in better.

NOTE. Speakers of Southern or BBC English should be careful always to give r its full value, and should guard against letting it colour their pronunciation of a preceding vowel.

10. l is dental, and so even more like a French than an English l. It does not have the ‘dark’ quality which in varying degrees an English l may have.

11. s is usually voiceless as in English sin, but there are situations in which it is voiced (therefore pronounced z), when followed by voiced phonemes (see below).

12. Doubled letters, like ss, nn, etc., should be so pronounced that both members of the combination are distinctly articulated, as s+s in English ‘less soap’, n+n in Eng. greenness.

2.3. Syllables

2.3.1. In many modern languages, there are as many syllables in a word as there are separate vowels and diphthongs. Indo-European follows this rule too:

swe-sōr, sister, skrei-bhō, write, ne-wā, new, ju-góm, yoke.

NOTE. According to Fortson (2004): “PIE grouped sounds into syllables in much the same way as Greek, Latin, Sanskrit and many other languages. In any given sequence of consonants and vowels, the vowels constituted the syllabic peaks, and were linked to a preceding consonant (if one was available) which formed the onset (beginning) of a syllable. If two or more consonants occurred together in the middle of a word, they were usually split between two syllables. In the abstract, a word of the structure VCCVCVCCVC would have been syllabified VC.CV.CVC.CVC. It is possible that certain consonant clusters could group together in the middle of a word as the onset of a syllable; if so, by a universal phonological principle they would have also been able to form word-initial onsets”.

2.3.2. Resonants can also be centre of a syllable. It is possible to hear similar sound sequences in English interesting (‘íntsting’), cattle (‘cattḷ’), bottom (‘bottṃ’), or Brighton (‘Brightṇ’), as well as in other modern languages, as in German Haben (‘Hab), Czech hlt, Serbian srpski, etc. In this kind of syllables, it is the vocalic resonant [r̥], [l̥], [m̥], or [n̥] –constrained allophones of [r], [l], [m], [n] –, the one which functions as syllabic centre, instead of a vowel proper:

k-di, heart, w-qos, wolf, de-k, ten, nō-m, name.

NOTE. Words derived from these groups, represented CRC, are unstable and tend to add auxiliary vowels before or after the resonants, i.e. C°RC or CR°C. Because of that, their evolutions differ greatly in modern IE languages. For example, dghwā, language, evolved probably as *d°nghwā, into PGmc. tung(w)ō, and later English tongue or German Zunge, and into Old Latin dingwa, and then the initial d became l in Classic Latin, written lingua, which is in turn the origin of Modern English words “linguistic” and “language”. For wqos (cf. Ved. vkas < PII wkas), it evolved either as *w°lkwos into PGmc. *wulxwaz (cf. O.H.G. wolf) or BSl. *wilkas (cf. O.C.S. vьlkъ), or as *wlukwos into Common Greek *wlukwos (cf. Gk. lykos), Ita. *wlupos (cf. Lat. lupus).

2.3.3. According to Ringe (2006), each sequence of one or more resonants was syllabified as follows. If the rightmost member of the sequence was adjacent to a syllabic (i.e. a vowel, on the initial application of the rule), it remained nonsyllabic, but if not, it was assigned to a syllable peak. The rule then iterated from right to left, the output of each decision providing input to the next.

NOTE. Ringe (2006): Forms of kwon-, dog, neatly illustrate the process: The zero grade was basically kwn- (since full-grade forms show that the high vocalic was an alternating resonant, not an underlying syllabic high vowel). The genitive singular kwn-ós, dog’s, of a dog, was syllabified as follows: the n was adjacent to a vowel and therefore remained nonsyllabic; consequently the w was not adjacent to a syllabic, and it therefore surfaced as syllabic u, giving kunós (cf. Skt. śúnas, Gk. kunós).  On the locative plural kwn-, among dogs, was syllabified as follows: the n was not adjacent to a vowel and therefore became syllabic ; consequently the w was adjacent to a syllabic and therefore remained nonsyllabic, giving kw- (cf. Skt śvásu). There are some exceptions to this rule, though.

2.3.4. Apart from the common vocalic resonant CRC, another, less stable sequence is found in PIE *C°RV CVRV/CRV; as, kerwos<*k°rwos, deer. Auxiliary vowels were sometimes inserted in difficult *CRC; as, cemjō<*gw°mjō, come, etc.

NOTE. “Some have proposed a ‘reduced IE vowel’, the so-called schwa secundum(Hirt 1900, Güntert 1916, Sturtevant 1943), although they were probably just auxiliary vowels, mere ‘allophonic vocoids’ initially necessary to articulate complex groups” (Adrados–Bernabé–Mendoza 1995-1998). It is commonly accepted that LIE dialects did in fact add an auxiliary vowel to this sequence at early times, probably before the first dialectal split: as early Indo-Iranian and Balto-Slavic dialects show, vocalisation of most *CRV groups had already happened when *CRC hadn’t still been vocalised, i.e. PIE *C°RV *CVRV.

The most unstable *CRV sequences found in LIE are possibly those with a resonant or glide as the initial consonant, i.e. *RRV; as, suffix -m°no-, m°rijar, die, etc. Although cf. also adjectival suffix (-t/s)-°mo-, ordinal sépt°mos, etc.

NOTE. Such irregular forms kept their apparent alternating pattern in post-LIE period, hence probably an auxiliary vowel was still inserted in the IEDs. The convention is to write the dot ° before the resonant, but in this grammar we prefer a simpler notation, with the dot below; since compounds of CRV cannot naturally include a resonant in IE, there is no possible confusion. From the examples above, it is written here conventionally mo- (v.i. §7.7.2), mijar, die (cf. Skt. mriyate, Av. miryeite, Gk. emarten, Lat. morior, O.C.S. mĭrǫ, mrěti, Lith. mĩrti), suffix -(t/s)-o- (v.i. §5.4), séptos, etc.

Most dialects show a common auxiliary vowel with maximal opening (in [a]) for the resonant, into a general CaRV, even in those dialects that show different outputs (as well as non-vocalisation) for CRC; i.e. m(a)rijar, -(t/s)-amo-, séptamos, etc.Adrados–Bernabé–Mendoza (1995-1998). As with consonant change, in this grammar the phonetically correct notation is therefore avoided in favour of the phonemically correct notation.

2.3.5. In the division of words into syllables, these rules apply:

a. A single consonant is joined to the following vowel or diphthong; as lon-dhom, land, rei-dhō, ride, etc.

b. Combinations of two or more consonants are regularly separated, and the first consonant of the combination is joined to the preceding vowel; as legh-trom, support, pen-qe, five, etc.

When a consonant is followed by a resonant or a glide, the consonants are not separated, even in the middle of a word and preceded by a vowel; as, a-gros,field, me-dhjos, middle.

c. In compounds, the parts are usually separated; as a--sta-tis, distance, from apo + statis.

2.3.6.The semivowels [j], [w] are more stable than resonants when they are syllable centres, i.e. [i] or [u].

NOTE. Both forms appear – like resonants – in a complementary distribution, i.e. as CIC and VJV, and never as ˟CJC or ˟VIV. Some authors make a distinction between consonantal [j], [w], and vocalic [i], [u]; see Schmitt-Brandt (Die Entwicklung des Indogermanischen Vokalsystems, 1967), Szemerényi (1985), or Mayrhofer (“Lautlehre (Segmentale Phonologie des Indogermanischen)”, in Indogermanische Grammatik I, Cogwill-Mayrhofer 1986).

When they are pronounced lento, they give the allophones (or allosyllables) ij, uw. Examples of alternating forms in PIE include médhijos (cf. Lat. medius), and medhjos (cf. O.Ind. mádhjas or Gk. μέσσος); dwōu, two (cf. Goth. twai, Gk. δω-), and duwōu (cf. O.Ind. duva, Gk. ō < dúwō, Lat. duo).

NOTE. The so-called Sievers’ Law was behind most of these forms; it explains that the weight of a syllable in LIE affected the pronunciation of following consonant clusters consisting of a consonant plus a glide before a vowel (e.g. -tjo-, -two-): if the syllable before the cluster was heavy (i.e. if it ended in -VCC or - C), the vocalic equivalent of the glide was inserted into the cluster (yielding -tijo-, -tuwo-). One of the conditions is that the rule only applied when the glide began the final syllable of the word.

It is the same rule as Lindeman’s Law, whereby monosyllables beginning with consonant plus glide (like kwōn, dog, or djēus, sky) had the cluster broken up in the same way as Sievers’ Law (kuwn, dijus) if the word followed a word ending in a heavy syllable. Descendants of both alternating forms might be preserved in the same dialect, or be found in different different dialects. Lindeman’s Law can be interpreted as the sandhi equivalent to Sievers’ Law; the variant dijus is determined by the final position of the preceding word: on one hand we have ##...#dijus ## and ##...VR#dijus##, on the other ##...C#djēus##. See Fortson (2004) and Meier-Brügger (2003).

2.4. Prosody

2.4.1. The Indo-European verse is quantitative: it is based, that is to say (as in Latin, Greek or Sanskrit), on a regular arrangement of long and short syllables and not, as in English, of stressed and unstressed syllables.

Syllables are distinguished according to the length of time required for their pronunciation. Two degrees of quantity are recognised, long and short.

NOTE. To distinguish long and short syllables more clearly from long and short vowels the former may be referred to as heavy and light respectively(corresponding to the Sanskrit terms guru and laghu, IE crāand leghú, respectively).

In syllables, quantity is measured from the beginning of the vowel or diphthong to the end of the syllable. Such distinctions of long and short are not arbitrary and artificial, but are purely natural, a long syllable requiring more time for its pronunciation than a short one.

2.4.2. A syllable is long or heavy usually,

a. if it contains a long vowel; as,  mā-tr, mother, --, hide,

b. if it contains a diphthong; as, lai-wós, left, oi-nos, one,

c. if it is followed by two or more consonants (even in another word); as, dherghs, shit, korm-nos, bleach.

2.4.3. A syllable is short or light usually if it contains a short vowel (or vocalic resonant) followed by a vowel or by a single consonant; as, dre-, cut, or e-í-mi, go; or q-mis, worm, c-tis, march.

NOTE. In old compositions, sometimes final short vowels are found as heavy syllables; as, Skt. deví etu, or vocat. vki, tanu, cf. Lindeman (1987) or Beekes (“On laryngeals and pronouns”, KZ96, 1982). They are possibly glottal stops, remains of the old merged LIE laryngeal *H, i.e. *dewíH, *wr̥kiH, etc. “The Rig Veda preserves many words that must scan as though a laryngeal or some remnant of a laryngeal (like a glottal stop) were still present between vowels, a phenomenon called laryngeal hiatus”. For example, Skt. vtas ‘wind’ must sometimes scan trisyllabically as va’atas, which comes from earlier pre-PII *weHn̥tos or PII ʔatas < PIE *h2weh1n̥tos NWIE wentos; although for Ringe (2006) from Lat. ventus, Welsh gwynt,  PGmc. *windaz, only NWIE wentós or wēntos (cf. Proto-Toch. *wyentë) could be reconstructed.

2.5. Accent

2.5.1. There are accented as well as unaccented words. The last could indicate words that are always enclitic, i.e., they are always bound to the accent of the preceding word, as -qe, and, -w, or; while another can be proclitics, like prepositions.

2.5.2. Evidence from Ancient Greek, Vedic Sanskrit and Balto-Slavic accent let us reconstruct a LIE pitch (also tonic or musical) accent system, with only one, acute accent. Late Indo-European was therefore a stress language in which syllable strength was chiefly a matter of pitch differences: the accented syllable was higher in pitch than the surrounding syllables.

NOTE 1. For Beekes (1995): “There are several indications that Proto-Indo-European was a tone language at some time in its development. The accent-systems of both Sanskrit and Greek already give reason enough to surmise that this may have been the case.”

According to Clackson (2007): “Qualitatively our best evidence for PIE accent comes from two of the oldest and most conservative branches: Greek and Vedic Sanskrit. For both languages there is a large body of texts with word-accents marked and adequate metalinguistic descriptions of the nature of the accentual system. The accent of both Greek and Sanskrit was a mobile pitch-accent type, but there were differences between the two systems (…) Since the two morae of some of the Greek circumflex nuclei have arisen from contraction of two syllables, it seems reasonable to assume that the syllable-based accent of Sanskrit is original (…).”

We can therefore assume that the attested distinction between acute and circumflex accent in Ancient Greek and Baltic languages does not come from the LIE period, but were late independent dialectal developments. According to this description of events, the Greek and Indic systems were lost: Modern Greek has a pitch produced stress accent, and it was lost entirely from Indic by the time of the Prākrits. Balto-Slavic retained LIE pitch accent, reworking it into the opposition of ‘acute’ (rising) and ‘circumflex’ (falling) tone, and which, following a period of extensive accentual innovations, yielded pitch-accent based system that has been retained in modern-day Lithuanian and West South Slavic dialects. Some other modern Indo-European languages have pitch accent systems; as, Swedish and Norwegian, deriving from a stress-based system they inherited from Old Norse, and Punjabi, which developed tone distinctions that maintained lexical distinctions as consonants were conflated.

NOTE 2. A possibility is that PIE (or, more exactly, PIH) was a tonal language, i.e. that it had more than the limited word-tone system usually called pitch-accent. This position was argued by Szemerényi (1985), Lubotsky (The system of nominal accentuation in Sanskrit and Proto-Indo-European, 1988) and by Kortlandt (“The laryngeal theory and Slavic accentuation” in Bammesberger (ed.), 1988). They are mainly based on Sanskrit accentual system and typological considerations, since such a system would account for the old ablauting patterns found in PIE.

2.5.3. The accent is free, but that does not mean anarchy. On the contrary, it means that each non-clitic word has an accent and only one accent, and one has to know – usually by way of practice – where it goes. Its location usually depends on the inflectional type to which a given word belongs.

NOTE. The term free here refers to the position of the accent—its position is (at least partly) unpredictable by phonological rules, i.e. it could stand on any syllable of a word, regardless of its structure. Otherwise homophonous words may differ only by the position of the accent, and it is thus possible to use accent as a grammatical device.

2.5.4. The place of the original accent is difficult to reconstruct, and sometimes different positions are attested. According to Clackson (2007), comparison of Germanic, Baltic, Slavic, Greek and Sanskrit allows us to reconstruct the place of the PIE word accent with confidence, what let us deduce some properties of the accentual system:

a) The accent can fall on any element which functions as a syllabic nucleus.

b) The accent can fall on any syllable of a word.

c) No word has more than one accent.

2.5.5. According to Ringe (2006), thematic nominal (i.e. those ending in the thematic vowel) had the accent on the same syllable throughout the paradigm; thematic verb stems also have generally a fixed accent.

Some athematic verb stems and nominal have fixed accent (mostly on the root), but most had alternating accent; there were different patterns, but in all of them the surface accent was to the left in one group of forms (the nominative and accusative cases of nominal, the active singular of verbs) and to the right in the rest.

Stems and endings can be underlyingly accented or not, and words with no underlying accent are assigned accent on the leftmost syllable by default.

NOTE. According to Lehmann (1974): “The location of the high pitch is determined primarily from our evidence in Vedic; the theory that this was inherited from PIE received important corroboration from Karl Verner’s demonstration of its maintenance into Germanic (1875). Thus the often cited correlation between the position of the accent in the Vedic perfect and the differing consonants in Germanic provided decisive evidence for reconstruction of the PIE pitch accent as well as for Verner’s law, as in the perfect (preterite) forms of the root *deyk-, ‘show’.”






1 sg.





1 pl.






2.6. Vowel Change

2.6.1. The vowel grade or ablaut is normally the alternation between full, zero or lengthened grade vocalism. Proto-Indo-European had a regular ablaut sequence that contrasted the five usual vowel sounds called thematic, i.e. e/ē/o/ō/. This means that in different forms of the same word, or in different but related words, the basic vowel, a short e, could be replaced by a long ē, a short o or a long ō, or it could be omitted (transcribed as ).

NOTE. The term Ablautcomes from Ger. Abstufung der Laute, ‘vowel alternation’. In Romance languages, the term apophony is preferred.

In Romance languages, theme is used instead of stem. Therefore, theme vowel and thematic refer to the stem endings. In the Indo-European languages, a common conventional nomenclature is that thematic stems are those stems that have the common “theme vowel”, i.e. the e/o ending. Athematic stems lack that theme vowel, and attach their inflections directly to the stem itself.

2.6.2. When a syllable had a short e, it is said to be in the e grade; when it had no vowel, it is said to be in the zero grade, when in o, in o grade, and they can also be lengthened. The e-grade is sometimes called full grade.

NOTE. While changes in the length of a vowel (as e--ē, o--ō) are usually termed quantitative ablaut, changes in the quality of a vowel (as e-o or ē-ō), are termed qualitative ablaut.  Because qualitative changes are more frequent than lengthened-grades, these forms are usually termed e-grade or o-grade for convenience (Fortson 2004).

A classic example of the five grades of ablaut in a single root is provided by the following different case forms of IE patr, father, and patōr, fatherless.

Ablaut grade


Greek             (translit.)


e-grade or full grade





lengthened e-grade















lengthened o-grade





NOTE. Another example of the common Ablaut is t-stem nepot-, grandson, which gives lengthened grade Nominative, nep-ōts, full-grade Genitive nép-ot-os, and zero-grade feminine nep-t-is, grand-daughter. The study of declensions and practice with vocabulary should help the reader learn such alternations.

2.6.3. Synoptic table of common examples of different vowel grades (adapted from Adrados–Bernabé–Mendoza 1995-1998):

Vowel Grade

Full (F)

Zero ()

Lengthened  (L)

e/o - - ē/ō




je/jo - i - /




we/wo - u - /




ei/oi/ai - u/i - ēi/ōi/āi




eu/ou/au - u/i - ēu/ōu/āu




au/ai - u/i - āu/āi




ā/ē/ō - a - ā/ē/ō




ēi/ōi - ū/ī - ēi/ōi




2.6.4. There are also some other possible vowel grade changes, as a-grade, i-grade and u-grade, which usually come from old root endings, rather than from systematised phonetic changes.

NOTE. It seems that the alternation full-grade/zero-grade in PIE was dependent on the accent. Compare klewos/klutós, eimi/imés, patér/patrós, etc., where the unstressed morpheme loses its vowel. This happens only in the oldest formations, though, as Late Indo-European had probably lost this morphological pattern, freezing many older ablauting words and creating a new (more stable) vocabulary without changes in accent or vowel grade.

2.6.5. As we have seen, vowel change was common in Proto-Indo-European. In many words the vowel varies because of old ablauting forms that gave different derivatives.

So for example in o-grade domos, house, which gives dómūnos, lord, as Lat. dominus, Skt. dámūnas; but full grade root dem-, which gives demspóts, master, lord (from older gen. *dems) as Gk. δεσπότης (despótēs), Skt. dampati, Av. dəg patōiš, (with fem. demspotnja).

NOTE. The forms attested in Indo-Iranian (and maybe Greek) come from i-stem potis, probably derived from the original Late PIE form dems-póts, cf. ghósti-pots, guest, as Lat. hospēs, hospitis, O.Russ. gospodь<*-ostьpot-; compare, for an original PIE ending -t in compounds, Lat. sacerdōs < *sakro-dhots, O.Ind. devastút-, “who praises the gods”, etc. The compound is formed with pot-, lord, husband, and pot-nja, mistress, lady.

2.6.6. Different vocalisations appeared in IE dialects in some phonetic environments, especially between two occlusives in zero-grade; as e.g. skp-, which evolved as Lat. scabo or Got. skaban.

NOTE. According to Fortson (2004): “In word-initial consonant clusters consisting of two stops plus a resonant, a prop vowel was introduced between the two stops to break up the cluster; this vowel was introduced between the two stops to break up the cluster; this vowel is called “schwa secundum” (…) . For example, one of the forms of numeral ‘four’ was *kwtu̯or-, which developed a schwa secundum to become *kwetu̯or- or *kwətu̯or-, yielding Lat. quattuor and Homeric Gk. písures (as opposed to Gk. téssares from a different form, *kwetu̯or-).”

Although the dialectal solutions to such consonantal groups aren’t unitary, we can find some general PIE timbres. A general a; an i with a following dental (especially in Gk. and BSl.); or u, also considered general, but probably influenced by the context, possibly when in contact with a labial, guttural or labiovelar. Adrados–Bernabé–Mendoza (1995-1998).

2.6.7. Sometimes different reconstructions might account for some vowel differences, most frequently in combinations of *RH or *HR; as, *lawō for lowō, wash, *Sos for Samos, summer, *kwos for kerwos, deer, etc.

NOTE. Different reconstructions might be equally valid, depending on the criteria employed. Sometimes different PIE language stages have to be taken into account; as, for root neqt-, night, a common PIH *noqts is reconstructible, which had a genitive in *neqts according to Hitt. nekut; however, pre-LIE shows a generalised non-ablauting pattern; cf. O.Gk. nuks, nuktós, O.Lat. nox, noctis. The newer i-stem noqtis was the general post-LIE (and later also PII, NWIE) form, without accent-ablaut changes; cf. O.Ind. nakti, Gmc. naxti, Sla. notjь, Bal. nakti. See below §4.7 for a discussion on the reconstruction of root nouns.

2.7. Consonant Change

2.7.1. Regarding consonant change, different similar reconstructions might appear, too. Some might not fit into a single LIE original word; as, ghortos, garden (cf. Gk. khortos, Lat. hortus, O.Ir. gort), and ghordhos, enclosure (cf. Gk. khortis, Lith. gardas, O.C.S. gradu, Goth. gards, Phry. -gordum, Alb. garth).

NOTE. They have been explained as one original form borrowed with a (dialectal) consonant change into other dialects, but it is more likely that both forms were found in LIE.

2.7.2. The so called s-mobile refers to the phenomenon of alternating word pairs, with and without s before initial consonants, in roots with similar or identical meaning. This ‘moveable’ prefix s- is always followed by another consonant. Typical combinations are with voiceless stops (s)p-, (s)t-, (s)k-, with liquids and nasals, (s)l-, (s)m-, (s)n-; and rarely (s)w-.

NOTE. Examples include (s)ten-, cf. with s- O.Ind. stánati, Gk. sténō, O.Eng. stenan, Lith. stenù, O.Sla. stenjo, and without s- in O.Ind. tányati, Gk. Eol. ténnei, Lat. tonare, O.H.G. donar, Cel. Tanaros (name of a river). For (s)pek-, cf. O.Ind. spáśati, Av. spašta, Gk. skopós (<spokós), Lat. spektus, O.H.G. spehon, without s- in O.Ind. páśyati, Alb. pashë. For (s)ker-, cf. O.Ind. ava-, apa-skara-, Gk. skéraphos, O.Ir. scar(a)im, O.N. skera, Lith. skiriù, Illyr. Scardus, Alb. hurdhë (<*skd-), without s- in O.Ind. knáti, Av. kərəntaiti, Gk. keíro, Arm. kcorem, Alb. kjëth, Lat. caro, O.Ir. cert, O.N. horund, Lith. kkarnà, O.Sla. korŭcŭ, Hitt. kartai-, and so on. Such pairs with and without s are found even within the same branch, as Gk. (s)tégos, ‘roof’, (s)mikrós, ‘little’, O.Ind. (s)t, ‘star’, and so on.

NOTE. Some scholars posit that it was a prefix in PIE (which would have had a causative value), while others maintain that it is probably caused by assimilations of similar stems – some of them beginning with an s-, and some of them without it. It is possible, however, that the original stem actually had an initial s, and that it was lost by analogy in some situations, because of phonetic changes, probably due to some word compounds where the last -s of the first word assimilated to the first s- of the second one. That helps to explain why both stems (with and without s) are recorded in some languages, and why no regular evolution pattern may be ascertained: so for example in wqons spekjont, they saw wolves, becoming wqons ‘pekjont. Adrados–Bernabé–Mendoza (1995-1998).

2.7.3. In a cluster of two consonants differing in voicing, the voicing of the first is assimilated to that of the second.

Voiceless s was assimilated to voiced z before a voiced consonant; as, nisdos [‘niz-dos], nest, misdhom [‘miz-dhom], meed, salary, or osdos [‘oz-dos], branch.

Voiced stops become voiceless when followed by a voiceless consonant: e.g. agtós [ak-‘tos] (cf. Gk. ακτος (aktos), Lat. actus). The same happens with voiced aspirates, as in leghtrom, support (cf. Gk. lektron, O.H.G. Lehter or from the same root Lat. lectus); or nictós, washed (cf. Gk. a-niptos <*n̥-niqtos, ‘unwashed’, O.Ir. necht).

Voiceless stops become voiced before voiced consonants; as, ped- in zero-grade -pd-, cf. Gk. επιβδα (epi-bd-a), Av. frabda, ‘forefoot’.

Voiced and voiceless stops are pronounced alike in final position; as, qid [kwit] (cf. O.Ind. cit), or pod, foot (cf. voiceless O.Ind. nom. pāt, after having lost the final -s).

NOTE. Although the accuracy of some allophones in Late Indo-European is certain, for practical reasons the phonetically correct notation is therefore avoided in favour of the phonemically correct notation. We deem that to write them as a general rule, like writing ‘thə or ‘thi’ for English the, or ‘dogz’ for dogs, while possibly helpful to show the actual pronunciation, would probably be an obstacle to the understanding of the underlying etymology; also, such  phonetical variations exist naturally, and don’t need to be supported by the orthography.

2.7.4. A sequence of two dentals -TT- (such as -tt-, -dt-, -tdh-, -ddh-, etc.) was eliminated in all Indo-European dialects, but the process of this suppression differed among branches: Vedic Sanskrit shows little change, some others an intermediate -sT- (Iranian, Greek, Balto-Slavic) and others -ss- or -s- (Italic, Celtic, Germanic). Compounds were not affected by this trend; as, kréd-dhēmi, believe.

We find a common intermediate stage in Iranian, Proto-Greek (cf. Gk. st, sth, in pistis, oistha), and North-West Indo-European (cf. *Hed-tieats’, in Lat. est, Lith. esti, OCS jastŭ, and afield O.H.G. examples). Therefore, we can assume that PIE *d+t, *t+t, *dh+t   NWIE, PGk st; PIE *d+d, *t+d, *dh+d   NWIE, PGk sd; PIE *d+dh, *t+dh, *dh+dh   NWIE, PGk sdh.

Common examples are found in forms derived from PIE root weid-, know, see, which gave verb widējō, cf. Lat. vidēre, Goth. witan, O.C.S. viděti, Lith. pavydéti; p.p. wistós, seen, from wid--, cf. O.Ind. vitta-, but Av. vista-, O.Pruss. waist, O.Sla. věstъ, or Ger. ge-wiss, Lat. vīsus, O.Gk. ϝιστος (wistos), O.Ir. rofess, etc.; noun wistis, sight, vision, from wid-ti-, cf. Goth wizzi, Lat. vīsiō; Greek wistōr, wise, learned man, from wid-tor, cf. Gk. στωρ (hístōr)<*ϝίστωρ (wístōr), PGk wistorjā, history, from Gk. στορία (historía); Imp. wisdhi! know!, from wid-dhi, cf. O.Ind. viddhí, O.Gk. ϝίσθι (wísthi), O.Lith. veizdi, and so on.

NOTE. An older PIE *TT → *TsT has been proposed, i.e. that the cluster of two dental stops had a dental fricative s inserted between them (giving *-tst- and *-dzd-). It is based on some findings in Hittite, where cluster tst is spelled as z (pronounced ts), as in PIH *h1ed-te, ‘eat! *h1ette *h1etste Old Hitt. ēzten (pronounced étsten), or Ved. Skt. attá (interpreted as from *atstá, where *s is lost). Cf. also for Indo-Iranian imperative *da-d-dhí ‘give!’ in L.Av. dazdi, O.Ind. dehí<dazdhi<*dadzdhi (Mayrhofer Lautlehre 1986), instead of the expected O.Ind. *daddhi. However, confirmation from a common LIE *-st- is found in Indo-Iranian too (which might be interpreted as previous *TsT where the initial *T is lost); as, O.Ind. mastis, “measure”, from *med-tis, or Av. -hasta-, from *sed-tós. This LIE evolution TT ( TsT)? sT was overshadowed by dialectal developments, v.s. §1.7.2.III.

2.7.5. It seems that simplification of geminated PIE *-ss- occurred already in LIE, as Greek and Indo-Iranian dialects show. However, in this book the written gemination is considered the most conservative approach. Only the attested simplification of gemination is reconstructed; as, esi for es-si, you are.

NOTE. So, from *essi we have O.Ind. ási, Av. ahi, Gk. ε <*esi (Hom. and Dor. σσί are obviously analogic forms), etc. That form from es- is reconstructed e.g. by Adrados–Bernabé–Mendoza (1995-1998), Fortson (2004), Cardona (2004), Ringe (2006), among others. It is therefore to be pronounced with a simple /-s-/, and written accordingly -s-.

This is not the only solution to gemination in PIE, though, as shown by e.g. Lat. amassō, propriassit, with original IE gemination after Kortlandt. Therefore, the fact that *-ss- is simplified into -s- in some attested words does not confirm that the simplification occurred necessarily and always in LIE (or IED) times, because it could have occurred later, although it shows a clear trend toward simplification.

2.7.6. Consonant clusters *KsK were simplified by loss of the first stop; as, present stem of prek-, ask, pk-sk- [pr̥-‘sk] (cf. Lat. poscit, Skt. pr̥ccháti).

2.7.7. Word-final -n was often lost after ō; as, kwō(n), dog (cf. O.Ir. ); or dhghomō(n), man (cf. Lat. homō); this loss was not generalised, although it seems that it was already common in Late Indo-European.

NOTE. Fortson (2004): PIE forms where the *-n disappeared, like the word for ‘dog’ above, are written by Indo-Europeanists variously with or without the n, or with n in parentheses:” kwōn or kwō or kwō(n). We prefer to write them always with -n by convention.