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.
Phrases and idioms:
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.
Derivatives:
triggered adj.
Etymology: 17th-c. tricker f. Du. trekker f. trekken pull: cf. TREK