Old Irish was affected by a series of phonological changes that radically altered its appearance compared with Proto-Celtic and older Celtic languages (such as Gaulish, which still had the appearance of typical early Indo-European languages such as Latin or Ancient Greek). The changes occurred at a fairly rapid pace between 350 and 550 CE.
Summary of changes
A capsule summary of the most important changes is (in approximate order):
Syllable-final (from PIE , ) assimilated to the following phoneme, even across word boundaries in the case of syntactically connected words. Voiceless stops became voiced: > . Voiced stops became prenasalised . They were reduced to simple nasals during the Old Irish period. Before a vowel, was attached to the beginning of the syllable. Lenition of all single consonants between vowels. That applied across word boundaries in the case of syntactically connected words. Stops became fricatives. became (later lost unless the following syllable was stressed). was eventually lost (much later). became a nasalised continuant (; perhaps or ). remained, but the non-lenited variants were strengthened to (see Old Irish phonology). Extensive umlaut ("affection") of short vowels, which were raised or lowered to agree with the height of following Proto-Celtic vowels. Similarly, rounding of to or often occurred adjacent to labial consonants. Palatalization of all consonants before front vowels. Loss of part or all of final syllables. Loss of most interior vowels (syncope).
They led to the following effects: Both the palatalised ("slender") and lenited variants of consonants were phonemicised, multiplying the consonant inventory by four (broad, broad lenited, slender, slender lenited). Variations between broad and slender became an important part of the grammar: in masc. -stems: "son" (nom. acc.) vs. (gen.), "back" (nom. acc.) vs. (gen.), cf. Latin (nom.), (acc.) vs. (gen.); in fem. -stems: "tribe, people" (nom.) vs. (acc. dat.), "pig" (nom.) vs. (acc. dat.); in -stems: "father" (gen.) vs. (nom. acc. dat.). Lenition and nasal assimilation across word boundaries in syntactically connected words produced extensive sandhi effects (Irish initial mutations). The variations became an important part of the grammar. Both umlaut (vowel affection) and especially syncope radically increased the amount of allomorphy found across declensions and conjugations. The most dramatic deviations are due to syncope: compare "they say" vs. "they do not say" or "he surpasses" vs. "he does not surpass" (where the stressed syllable is boldfaced).
Examples of changes
The following are some examples of changes between Primitive Irish and Old Irish. { | class="wikitable" ! Primitive Irish !! Old Irish !! Meaning |- | || || daughter |- | || || priest |- | || || son (gen.) |- | || || poet (gen.) |- | || || genitive of Lug(u)id (name) |- | || || genitive of Anblamath (name) |- | || || genitive of name |}
Allomorphy
These various changes, especially syncope, produced quite complex allomorphy, because the addition of prefixes or various pre-verbal particles (proclitics) in Proto-Celtic changed the syllable containing the stress: According to the Celtic variant of Wackernagel's law, the stress fell on the second syllable of the verbal complex, including any prefixes and clitics. By the Old Irish period, most of this allomorphy still remained, although it was rapidly eliminated beginning in the Middle Irish period.
Among the most striking changes are in prefixed verbs with or without pre-verbal particles. With a single prefix and without a proclitic, stress falls on the verbal root, which assumes the deuterotonic ("second-stressed") form. With a prefix and also with a proclitic, stress falls on the prefix, and the verb assumes the prototonic ("first-stressed") form. Rather extreme allomorphic differences can result:
{ | class="wikitable" |+ Example differences between deuterotonic and prototonic forms of various verbs. Stress falls directly after the center dot or hyphen. ! Earlier form !! Deuterotonic !! Meaning !! Prototonic !! Meaning |- | < PIE *-bʰeronti || || they say || || they do not say |- | || || he rests || || he does not rest |- | || || he surpasses || || he does not surpass |- | < PIE *-logʰeyeti || || he pardons || || he does not pardon |- | ...|| || he may do || || he may not do |}
The following table shows how these forms might have been derived: