arbalest(n = noun.artifact) arbalist, ballista, bricole, catapult, mangonel, onager, trebuchet, trebucket - an engine that provided medieval artillery used during sieges; a heavy war engine for hurling large stones and other missiles;
is a kind of engine

   A crossbow, consisting of a steel bow set in a shaft of wood, furnished with a string and a trigger, and a mechanical device for bending the bow. It served to throw arrows, darts, bullets, etc. Fosbroke. [1913 Webster]

arbalest, n. (also arblast) hist. a crossbow with a mechanism for drawing the string.

Etymology:
OE arblast f. OF arbaleste f. LL arcubalista f. arcus bow + BALLISTA