What is "asinus onager"

Onager \On"a*ger\, n.; pl. L. Onagri, E. Onagers. [L. onager, onagrus, Gr. ?.]

1. (Rom. Antiq.) A military engine acting like a sling, which threw stones from a bag or wooden bucket, and was operated by machinery.
   --Fairholt.

2. (Zo["o]l.) A wild ass of central Asia, especially the koulan ( Equus hemionus syn. Equus hemippus syn. Equus onager, formely Asinus onager).

Koulan \Kou"lan\, n. [Native name.] (Zo["o]l.) A wild horse ( Equus onager or Asinus onager) inhabiting the plains of Central Asia; -- called also gour, khur, and onager. [Written also kulan.]

Note: It is sometimes confounded with the dziggetai, to which it is closely related. It is gray in winter, but fulvous in summer. It has a well defined, dark, dorsal stripe, and a short, erect mane. In size, it is intermediate between the horse and ass.