the person on a military plane in the US air force who is responsible for aiming and dropping bombs （美国空军的）投弹手 a member of a low rank in the Royal Artillery (= a part of the British army that uses large guns) （英国皇家炮兵的）下士
Word Originmid 16th cent. (denoting a soldier in charge of a bombard, an early form of cannon): from French, from Old French bombarde ‘cannon’, probably based on Latin bombus ‘booming, humming’, from Greek bombos, of imitative origin.