n. (pl. -ies) 1 a stupid or childish person. 2 a small gannet of the genus Sula. booby-hatch esp. US sl. a mental hospital. booby prize a prize given to the least successful competitor in any contest. booby trap 1 a trap intended as a practical joke, e.g. an object placed on top of a door ajar. 2 Mil. an apparently harmless explosive device intended to kill or injure anyone touching it. booby-trap v.tr. place a booby trap or traps in or on.
[ prob. f. Sp. bobo (in both senses) f. L balbus stammering ]