(f) Nasals: m (labial), n (dental), ñ (palatal), ɲ (velar), the last three in combination with similar consonants.
(a) As far as the vowels are concerned, Greek retains the original state of things more accurately than any other language. The sounds of short e and short o in Attic and Ionic were close, so that e + e contracted to a long close e represented by ει, o + o to a long close o represented by ου. In these dialects u, both long and short, was modified to ü, and they changed the long ā to ē, though Attic has ᾱ after ε, ι and ρ. In Greek ǝ appeared regularly as α, but under the influence of analogy often as ε and ο.
(b) The short diphthongs as a whole remained unchanged before a following consonant. Before a following vowel the diphthong was divided between the two syllables, the ι or υ forming a consonant at the beginning of the second syllable, which ultimately disappeared. Thus from a root dheu- “run” comes a verb θέω for θε-ϝω, from an earlier *θευ-ω. The corresponding adjective is θοός “swift,” for θο-ϝο-ς, from an earlier *θου-ο-ς. The only dialect which kept the whole diphthong in one syllable was Aeolic. The long diphthongs, except at the ends of words, were shortened in Attic. Some of these appear merely as long vowels, having lost their second element in the proethnic period. Apparent long diphthongs like those in λῃτουργία, σᾡζω arise by contraction of two syllables.
(c) The consonants suffered more extensive change. The voiced aspirates became unvoiced, so that bh, dh, ḡh, gh, gṷh are confused with original ph, th, ǩh, qh, qṷh: I.E. *bherō (Skt. bharāmi) is Gr. φέρω; I.E. *dhūmos (Skt. dhūmas), Gr. θῡμος; I.E. *ǧhimo- (Skt. hima-), Gr. (δυσ)-χιμο-ς; I.E. *stigh- (Skt. stigh-), Gr. στίχες; I.E. gṷhen- (Skt. han-), Gr. θείνω (probably), φόνος. The palatal and velar series cannot be distinguished in Greek; for the differences between them resort must be had to languages of the satem-group, such as Sanskrit, Zend or Slavonic, where the palatals appear as sibilants (see [Indo-European Languages]). The labio-velar series present a great variety of forms in the different Greek dialects, and in the same dialect before different sounds. Thus in Attic before o vowels, nasals and liquids, the series appears as π, β, φ; before e and i vowels as τ, β (δ), θ; in combination with u, which led to loss of the ṷ by dissimilation, κ, γ χ. Thus ἕπομαι corresponds to the Latin sequo-r, apart from the ending; βοῦς to Latin bos (borrowed from Sabine), English cow; φόνος “slaughter,” ἕπεφνον, old Irish gonim, “I wound.” Parallel to these forms with p are forms in the Italic languages except Latin and Faliscan, and in the Cymric group of the Celtic languages. The dental forms τ, δ, θ stand by themselves. Thus τις (from the same root as ποῦ, ποῖ, πόθεν, etc.) is parallel to the Latin quis, the Oscan pis, old Irish cía, Welsh pwy, “who?” “what?”; Attic τέτταρες, Ionic τέσσερες “four” is parallel to Latin quattuor, Oscan πετορα, old Irish cethir, old Welsh petguar; τίσις is from the same root as ποινή. For the voiced sound, β is much more common than δ before e and i sounds; thus βίος “life,” from the same root as Skt. jīvas, Latin vīvus; βιός “bowstring,” Skt. jyā, &c. In Arcado-Cyprian and Aeolic, π and β often precede e and i sounds. Thus parallel to Attic τέτταρες Lesbian has πέσσυρες, Homer πίσυρες, Boeotian πέτταρες; Thessalian βέλλομαι, Boeotian βείλομαι alongside of Attic βούλομαι, Lesbian βόλλομαι, Doric βώλομαι and also δήλομαι. In Arcadian and Cyprian the form corresponding to τις was σις, in Thessalian κις, where the labialization was lost (see the article on [Q]).
A great variety of changes in the stopped consonants arose in combination with other sounds, especially ḭ (a semivowel of the nature of English y), ṷ (w) and s; -τḭ-, -θḭ- became first -σσ- and later -σ- in Attic Greek, -ττ- in Boeotian (the precise pronunciation of -σσ- and -ττ- is uncertain): Attic ὁ-πόσος, earlier ὁ-πόσσος, Boeotian ὁ-πόττος, from the same stem as the Latin quot, quotiens; Homeric μέσσος, Attic μέσος from *μεθιος, Latin medius; -κḭ-, -χḭ- became -σσ-, Attic -ττ-: πίσσα “pitch,” Attic πίττα from *πίκḭα, cp. Latin pix, picis, ἐλάσσων, Attic ἐλάττων comparative to ἐλαχύς. δḭ and γḭ became ζ: Ζεύς (Skt. Dyāuṣ) ἐλπίζω from ἐλπίς, stem ἐλπιδ- “hope,” μαστίζω from μάστιξ, stem μαστῑγ- “lash.”
(d) The sound ṷ was represented in the Greek alphabet by ϝ, the “digamma,” but in Attic and Ionic the sound was lost very early. In Aeolic, particularly Boeotian and Lesbian, it was persistent, and so also in many Doric dialects, especially at the beginning of words. When the Ionic alphabet was adopted by districts which had retained ϝ, it was represented by β: βρόδον Aeolic for ῥόδον, i.e. ϝρόδον. In Attic it disappeared, leaving no trace; in Ionic it lengthened the preceding syllable; thus in Homer ὑποδείσας is scanned with ο long because the root of the verb contained ϝ: δϝει-. Attic has ξένος, but Ionic ξεῖνος for ξένϝος. Its combination with τ became -σσ-, Attic and Boeotian -ττ-, in τέσσερες, τέτταρες, πέτταρες for I.E. gṷetu-.
But the most effective of all elements in changing the appearance of Greek words was the sound s. Before vowels at the beginning, or between vowels in the middle of words, it passed into an h sound, the “rough breathing.” Thus ἑπτά is the same word as the Latin septem, English seven; ἅλ-ς has the same stem as the Latin sal, English sal-t; εὕω for εὐhω is the same as the Latin uro (*eusô). Combined with i or ṷ also it passes into h; ὑμήν, Skt. syūman, “band”; ἡδύς, Doric ἆδύς, Latin suā(d)vis, English sweet; cp. οἴκοιο for *ϝοικοḭο, νηός, Lesbian ναῦος “temple,” through ναϝός from *νασϝο-ς connected with ναίω “dwell.” Before nasals and liquids s was assimilated: μει-δάω, Latin mi-ru-s, English smile; νίφα, Latin nivem, English snow; λήγω, Latin laxus, English slack; ῥέω from *sreu-ō of the same origin as English stream (where t is a later insertion), imperfect ἔῤῥεον for *esreṷom; cp. also φιλομμείδης, ἀγάννιφος, ἄλληκτος.
After nasals s is assimilated except finally; when assimilated, in all dialects except Aeolic the previous syllable is lengthened if not already long: Attic ἔνειμα, ἔμεινα for the first aorist *enemsa, *emensa; but τόνς, τάνς, &c., of the accusative pl. either remained or became in Aeolic τοίς, ταίς, in Ionic and Attic τούς, τάς, in Doric τώς, τάς; cp. τιθείς for *τιθέντς, βάς for *βάντς, είς “one” for *sem-s, then by analogy of the neuter *sens. Assimilation of σ to preceding ρ and λ is a matter of dialect: Ionic θαρσέω, but Attic θαρρῶ, and so also the Doric of Thera: ἔκελσα, but ἔστειλα for *ἔστελσα. With nasals ḭ affected the previous syllable: τεκταίνω (*τεκτṋḭω), where ṋ is the nasal of the stem τέκτων, itself forming a syllable (see the article [N] for these so-called sonant nasals). Before ḭ original m becomes n; hence βαίνω with n, though from the same root as English come. Original ḭ does not survive in Greek, but is represented by the aspirate at the beginning of words, ἁγνός = Skt. yajnas; medially after consonants it disappears, affecting the preceding consonant or syllable where a consonant precedes; between vowels it disappears. A sound of the same kind is indicated in Cyprian and some other dialects as a glide or transition sound between two vowels.
(e) The most remarkable feature in the treatment of the nasals is that when n or m forms a syllable by itself its consonant character disappears altogether and it is represented by the vowel α only: τατός, Latin tentus, α- negative particle, Latin in, English un; ἁ-πλόος has the same prefix as the Latin sim-plex (sṃ). The liquids in similar cases show λα or αλ and ρα or αρ: τέ-τλα-μεν, πέ-παλται; ἔδρακον, θρασύς, θάρσος.
The ends of words were modified in appearance by the loss of all stop-consonants and the change of final m to n, ἔδειξε, Latin dixit; ζυγόν, Latin iugum.