The Dative singular of masculine nouns is like the nominative; of feminine nouns, is like the genitive; as, tobar m. a well, d. s. tobar; clarsach f. a harp, g. s. and d. s. clarsaich; misneach f. courage, g. s. and d. s. misnich.
Particular Rules for the Dative of Feminine Nouns.—1. If e was added to the nominative in forming the genitive, it is thrown away in the dative; as, slat f. a rod, g. s. slaite—d. s. slait; grian f. the sun, g. s. greine, d. s. grein.
2. If the nominative suffered a syncope in forming the genitive, or if the last vowel of the genitive is broad, the dative is like the nominative; as, buidheann f. a company, g. s. buidhne, d. s. buidheann; piuthar f. a sister, g. s. peathar, d. s. piuthar.
The Vocative of masc. nouns is like the genitive; of feminine nouns is like the nominative; as, bàs m. death, g. s. bàis, v. s. bhais; cu m. a dog, g. s. coin, v. s. choin; grian f. the sun, v. s. ghaoth.
Plural Number.
Nominative. Masculine nouns which insert i in the gen. sing. have their nom. plur. like the gen. sing.; as, oglach m. a servant, g. s. oglaich, n. p. oglaich; fear m. a man, g. s. and n. p. fir. Many of these form their nom. plur. also by adding a short a to the nominative singular. Other masculine nouns, and all feminine nouns, have their nom. plural in a, to which n is added, euphoniæ causa, before an initial vowel[[37]].
Particular Rules for forming the Nom. Plur. in a or an.
1. By adding a to the nom. singular; as, dubhar m. a shadow, n. p. dubhara; rioghachd f. a kingdom, n. p. rioghachdan. Under this Rule, some nouns suffer a syncope; as, dorus m. a door, n. p. dorsa for dorusa.
2. Nouns ending in l or nn, often insert t before a; as, reul m. a star, n. p. reulta; beann f. a pinnacle, n. p. beannta. So lòn m. a marsh, n. p. lòintean.