trig·ger / ˈtrigər/ • n. a small device that releases a spring or catch and so sets off a mechanism, esp. in order to fire a gun: he pulled the trigger of the shotgun. ∎  an event or thing that causes something to happen: the trigger for the strike was the closure of a mine.• v. [tr.] (often be triggered) cause (an event or situation) to happen or exist: an allergy can be triggered by stress or overwork. ∎  cause (a device) to function.PHRASES: quick on the trigger quick to respond.DERIVATIVES: trig·gered adj.ORIGIN: early 17th cent.: from dialect tricker, from Dutch trekker, from trekken ‘to pull.’

trigger To initiate the operation of an electric circuit or device. Thus a signal supplied to the trigger input of a circuit may cause the circuit's output signal to be synchronized to this input.

trigger movable catch or lever. XVII (tricker). — Du. trekker, f. trekken pull; see -ER1.