Do you know ghouls from goblins and ghosts?
Asiatic wild ass, mid-14c., from Latin onager, from Greek onagros, from onos "ass" (related to Latin asinus, but the ultimate source is unknown) + agrios "wild," literally "living in the fields," from agros "field" (see acre).
(Equus hemionus onager), subspecies of the wild ass of Asia that ranged from northwest Iran to Turkmenistan. Pale-coloured and small, it has a short erect mane and fairly large ears. It was domesticated in ancient times but was replaced by the domestic horse and donkey. It now is found in limited numbers and may be approaching extinction. The name onager is sometimes used for the Asian wild ass (Equus hemionus). See also ass.