in the nominative and accusative feminine and in the genitive masculine, as an ḃó, the cow; an ḃean, the woman; mac an ḟir, (the) son of the man; ceann an ċapaill, the horse’s head (or the head of the horse).
(b) If a noun begins with s followed by a vowel, or by l, n, r, the s is replaced by t, in the nominative and accusative feminine and genitive masculine, and sometimes in the dative of both genders: an tsál, the heel; an tsúil, the eye; teaċ an tsagairt, the house of the priest; mac an tsaoir, the son of the artizan; do’n tsagart, to the priest; ar an tsléiḃ, on the mountain.
Strictly speaking, it is only in the dat. fem. that the s is replaced by t, but custom permits it in the masculine.
(c) If a noun begins with a vowel, the article prefixes t the nominative and accusative masculine, and h to the genitive feminine, as an t‑aṫair, the father; an t‑uisge, the water; an t‑eun, the bird; an t‑uan, the lamb; bárr na h‑uiḃe, the top of the egg; fuaċt na h‑aimsire, the coldness of the weather.
(d) When the noun begins with an eclipsable consonant (except d and t, the article generally eclipses when it is preceded by a preposition, as ar an gcnoc, on the hill; ó’n ḃfear, from the man. After the prepositions do and de aspiration takes place, not
- For the effects of gan and the article, see Syntax, par. 606 (b).