| |- | or | | |- | | | |- | | | |- | | | |} The consonants l, n, r The letters l, n, r are generally written double when they indicate tense sonorants and single when they indicate lax sonorants. Originally, it reflected an actual difference between single and geminate consonants, as tense sonorants in many positions (such as between vowels or word-finally) developed from geminates. As the gemination was lost, the use of written double consonants was repurposed to indicate tense sonorants. Doubly written consonants of this sort do not occur in positions where tense sonorants developed from non-geminated Proto-Celtic sonorants (such as word-initially or before a consonant). {| class="wikitable" |- !Old Irish !Pronunciation !English |- | | | |- | | | |- | | | |- | | | |- | | | |- | | | |- | | | |- | | | |} Geminate consonants appear to have existed since the beginning of the Old Irish period, but they were simplified by the end, as is generally reflected by the spelling. Eventually, however, ll, mm, nn, rr were repurposed to indicate nonlenited variants of those sounds in certain positions. Vowels Written vowels a, ai, e, i in poststressed syllables (except when absolutely word-final) all seem to represent phonemic . The particular vowel that appears is determined by the quality (broad vs. slender) of the surrounding consonants and has no relation to the etymological vowel quality: {|class="wikitable" ! Preceding consonant !! Following consonant !! Spelling !! Example |- | broad || broad || || "vengeance" (nom.) |- | broad || slender (in open syllable) || || |- | broad || slender (in closed syllable) || || "vengeance" (acc./dat.) |- | slender || broad || || "law" (acc.) |- | slender || slender || || "law" (gen.) |} It seems likely that spelling variations reflected allophonic variations in the pronunciation of . History Old Irish underwent extensive phonological changes from Proto-Celtic in both consonants and vowels. Final syllables were lost or transphonologized as grammatical mutations on the following word. In addition, unstressed syllables faced various reductions and deletions of their vowels. Grammar Old Irish is a fusional, nominative-accusative, and VSO language. Nouns decline for 5 cases: nominative, accusative, genitive, prepositional, vocative; 3 genders: masculine, feminine, neuter; 3 numbers: singular, dual, plural. Adjectives agree with nouns in case, gender, and number. The