/trig"euhr/ , n.
1. a small projecting tongue in a firearm that, when pressed by the finger, actuates the mechanism that discharges the weapon.
2. a device, as a lever, the pulling or pressing of which releases a detent or spring.
3. anything, as an act or event, that serves as a stimulus and initiates or precipitates a reaction or series of reactions.
4. Slang. triggerman.
5. quick on the trigger , Informal. quick to act or respond; impetuous; alert.
v.t.
6. to initiate or precipitate (a chain of events, scientific reaction, psychological process, etc.): Their small protest triggered a mass demonstration.
7. to fire or explode (a gun, missile, etc.) by pulling a trigger or releasing a triggering device: He accidentally triggered his rifle.
v.i.
8. to release a trigger.
9. to become active; activate.
[ 1615-25; earlier tricker trekker, equiv. to trekk ( en ) to pull + -er -ER 1 ]