1. (Equus hemionus) A wild ass (family Equidae), larger than the African ass, with a yellow-brown or red-brown coat, that formerly occurred throughout much of Asia but is now found only in the more arid steppe grasslands. Onagers are renowned for their speed, running at up to 70 km/h, but they cannot be tamed.

2. An ancient weapon resembling a catapult, powered by torsion produced on a beam thrust through a thick skein of twisted cords, that would hurl a stone from a cup or probably more usually a sling at the end of the beam.