Onager
Onager , noun
[Latin onager, onagrus, Greek {not transcribed}.]
1.
(Rom. Antiquities) A military engine acting like a sling, which threw stones from a bag or wooden bucket, and was operated by machinery. — Fairholt
2.
(Zoology) A wild ass of central Asia, especially the koulan (Equus hemionus syn. Equus hemippus syn. Equus onager, formerly Asinus onager).