onager

The Asiatic wild ass or hemione (Equus hemionus), an animal of the horse family native to Asia; specifically, the Persian onager, Persian wild ass, or Persian zebra (Equus hemionus onager).

[I]f the czigithai is not the ſame with the zebra, it may be the Aſiatic animal called onager or wild aſs. The onager ſhould not be confounded with the zebra; but I am uncertain whether the ſame remark is applicable to the onager and czigithai; for, from comparing the relations of travellers, it appears, that there are different kinds of wild aſſes, of which the onager is the moſt remarkable. […] The ſwiftneſs of the onager is mentioned by travellers, who remark, that he runs with ſuch rapidity as to eſcape the hunters, though mounted on horſes; […]

The onager, or wild aſs, is ſeen in ſtill greater abundance than the wild horſe; and the peculiarities of its kind are more diſtinctly marked than in thoſe of the tame one.

A military engine acting like a sling which threw stones from a bag or wooden bucket powered by the torsion from a bundle of ropes or sinews operated by machinery; a torsion catapult.

The onager, meaning "wild ass," derived its name from its powerful recoil, or kick, upon discharge; […] In addition, although Josephus described an onager in action hurling a 100-pound stone over 400 yards, most onagri achieved a shorter range than the ballista, thus exposing their crews to enemy archers.