The Collaborative International Dictionary of English v.0.48:

Sasin \Sa"sin\, n. (Zool.)
   The Indian antelope (Antilope bezoartica syn. Antilope
   cervicapra), noted for its beauty and swiftness. It has
   long, spiral, divergent horns.
   [1913 Webster] Sassaby

WordNet (r) 3.0 (2006):

Antilope cervicapra
    n 1: common Indian antelope with a dark back and spiral horns
         [syn: blackbuck, black buck, Antilope cervicapra]