in Indian mythology, is the horse with a huge trunk, on which Baly the giant rode.
Through these wide portals oft had Baly rode Triumphant from his proud abode, When, in his greatness, he bestrode The Aulay, hugest of four-footed kind. The Aulay-horse, that in his force With elephantine trunk, could bind And lift the elephant, and on the wind Whirl him away, with sway and swing, E'en like a pebble from the practised sling.
Southey: Curse of Kehama, xvi. 2.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894