We don't have synonyms for onagers yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are onager.
(n) :
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).
(n) :
(military, historical) 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.
(n) :
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).
(n) :
(military, historical) 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.