The Collaborative International Dictionary of English v.0.48:

Ai \A"i\, n.; pl. Ais. [Braz. a["i], ha["i], from the animal's
   cry: cf. F. a["i].] (Zool.)
   The three-toed sloth (Bradypus tridactylus) of South
   America. See Sloth.
   [1913 Webster] Aiblins