This word is normally feminine and follows the second declension, as shown in the first table below. The archaic masculine declension shown in the second table below is used especially in place names (e.g., Gort na nUbh(“Gortnanuv”), Co. Limerick, Munster).
Dinneen, Patrick S. (1927), “uḃ”, in Foclóir Gaeḋilge agus Béarla [Irish and English Dictionary], 2nd edition, Dublin: Irish Texts Society, page 1287; reprinted with additions 1996, →ISBN
Ó Dónaill, Niall (1977), “ubh”, in Foclóir Gaeilge–Béarla [Irish–English Dictionary], Dublin: An Gúm, →ISBN