The Collaborative International Dictionary of English v.0.48:

Gayal \Gay"al\, n. [Native name.] (Zool.)
   A Southern Asiatic species of wild cattle (Bibos
   frontalis).
   [1913 Webster]

WordNet (r) 3.0 (2006):

Bibos frontalis
    n 1: ox of southeast Asia sometimes considered a domesticated
         breed of the gaur [syn: gayal, mithan, Bibos
         frontalis]