n. & v.
n. 1 a movable device for releasing a spring or catch and so setting off a mechanism (esp. that of a gun). 2 an event, occurrence, etc., that sets off a chain reaction.
v.tr. 1 (often foll. by off) set (an action or process) in motion; initiate, precipitate. 2 fire (a gun) by the use of a trigger. quick on the trigger quick to respond. trigger fish any usu. tropical marine fish of the family Balistidae with a first dorsal fin-spine which can be depressed by pressing on the second. trigger-happy apt to shoot without or with slight provocation. triggered adj.
[ 17th-c. tricker f. Du. trekker f. trekken pull: cf. TREK ]