Noun
A military engine acting like a sling, which threw stones from a bag or wooden bucket, and was operated by machinery.
A wild ass, especially the koulan.
Source: Webster's dictionary; Onager : Mangonels are also sometimes referred to as Onagers. Source: Internet
The word 'Onager' is derived from the Greek word 'onagros' for wild ass, referring to the “kicking motion and force” that were recreated in the Mangonel's design. Source: Internet