A crossbow is essentially a bow mounted on an elongated frame (called a tiller or stock) with a built-in mechanism that holds the drawn bow string, as well as a trigger mechanism, which is used to release the string.
a cROSsBoW iS essEntiAlly A bow mounteD on an elOnGaTEd fRamE (calLeD a tiller or stock) With a built-iN mecHanISm thAt hOlds tHE draWn BOw striNg, As wELl aS A tRIgger mECHAnism, WhICh IS UsEd TO ReLEASE the strinG.