1. (noun)catapult, arbalest, arbalist, ballista, bricole, mangonel, onager, trebuchet, trebucket an engine that provided medieval artillery used during sieges; a heavy war engine for hurling large stones and other missiles Synonyms: arbalist, catapult, launcher, bricole, sling, onager, slingshot, arbalest, ballista, trebuchet, mangonel, trebucket