Plural Number.
Nominative.—General Rule. The nominative plural is formed by adding to the nominative singular a or an, written e or ean to correspond to a preceding small vowel; as, piobair m. a piper, n. p. piobairean; aimsir f. time, season, n. p. aimsirean. Some nouns suffer a contraction in the nominative plural; as, caraid m. a friend, n. p. càirdean; naimhaid m. an enemy, n. p. naimhdean; fiacail f. a tooth, n. p. fiaclan.
Particular Rules. 1. Some nouns, whose last consonant is l or n, insert t in the nominative plural; as, tuil f. a flood, n. p. tuilte; smuain f. thought, n. p. smuaintean; coille f. a wood, n. p. coilltean; àithne f. a command, n. p. àithnte. The t is aspirated in dail f. a plain, n. p. dailthean; sail f. a beam, n. p. sailthean.
2. Some nouns in air, chiefly such as form their genitive singular in ach, retain the same syllable in the nominative plural, and insert i after a; as,
| Cathair, f. a seat, | g. s. cathrach, | n. p. cathraichean. |
| Lasair, f. a flame, | g. s. lasrach, | n. p. lasraichean. |
| Nathair, f. a serpent, | g. s. nathrach, | n. p. nathraichean. |
So also cuid f. a part, from the g. s. codach, has the n. p. codaichean; athair m. a father, n. p. aithrichean; mathair f. a mother, n. p. maithrichean. To which add amhainn f. a river, n. p. aimhnichean; uisge m. water, n. p. uisgeachan; cridhe m. the heart, n. p. cridheachan.
The following nouns form their nominative plural irregularly; duine m. a man, n. p. daoine; righ m. a king, n. p. righre; ni m. a thing, n. p. nithe; cliamhuinn m. a son-in-law, or brother-in-law, n. p. cleamhna.
Genitive. The genitive plural of monosyllables and masculine polysyllables is twofold, like the nominative singular, and like the nominative plural; as, righ m. a king, g. p. righ or righre. The genitive plural of feminine polysyllables is like the nominative plural only; as, amhainn f. a river, g. p. aimhnichean. Suil f. the eye, has its g. p. sùl.
Dative. The dative plural is formed from the nominative plural by changing the final vowel into ibh; as, coluinn f. the body, n. p. coluinne, d. p. coluinnibh; cridhe m. the heart, n. p. cridheacha, d. p. cridheachaibh.