trebuchet
noun [ C ] military specialized uk/ˈtreb.ʊ.ʃeɪ/ us/ˈtreb.ʊ.ʃeɪ/
（古时攻城战中投掷大石块用的）投石机
a large device used in wars in the past for throwing large rocks, for example at the walls of a castle that was being attacked
The action of a trebuchet was similar to that of a giant catapult. 投石机的原理类似于一个巨大的弹弓。