An appellation given to several rabbis who ordinarily bear the prænomen Aḥa, under which name they are grouped; while others better known by the name of (or ) are as follows: 1. A Palestinian amora of the third century, contemporary of R. Ammi and R. Assi. He was judge of a divorce court (Giṭ. 5b). 2. A distinguished Babylonian teacher who flourished during the closing days of the amoraic period and at the beginning of the saboraic epoch. During his time the compilation and editing of the Babylonian Talmud, begun by Rab Ashi, gradually neared completion. His fame was not confined to his birthplace, Be-Ḥatim, or to his native country; for even in Palestine he was recognized as a great authority. Thus when the substance of a ritualistic controversy between him and Samuel b. Abbahu was submitted to a Palestinian academy for final adjudication, the rabbis decided in favor of the latter's opinion; but they added the significant warning, "Be careful of the views of R. Aḥai, for he is the light of the diaspora" (Ḥul. 59b). So, while but few of the sayings and teachings of his contemporaries are quoted in the Talmud, not less than ten distinct opinions of Rab Aḥai are incorporated in its pages (Yeb. 24a, 46a; Ket. 2b, 10a, 47a ḳid. 13a; Shebu. 41b; Zeb. 102b; Ḥul. 65b; Bek. 5a, 6a; Niddah, 33a). Rab Aḥai died in 506 ("Letter of Sherira"; Grätz, "Gesch. d. Juden," 1st ed., iv. 473). Brüll, "Jahrb." ii. 25 et seq., identifies him with Rab Aḥai b. Ḥanilai; but the great majority of ancient and modern rabbinical chronicles identify him with Rab Aḥai b. Huna.