| Noun | 1. | trigger - lever that activates the firing mechanism of a gungun - a weapon that discharges a missile at high velocity (especially from a metal tube or barrel) hair trigger - a gun trigger that responds with little pressure lever - a rigid bar pivoted about a fulcrum | |
| 2. | trigger - a device that activates or releases or causes something to happendevice - an instrumentality invented for a particular purpose; "the device is small enough to wear on your wrist"; "a device intended to conserve water" | |
| 3. | trigger - an act that sets in motion some course of events | |
| Verb | 1. | trigger - put in motion or move to act; "trigger a reaction"; "actuate the circuits"initiate, pioneer - take the lead or initiative in; participate in the development of; "This South African surgeon pioneered heart transplants" | |
| 2. | trigger - release or pull the trigger on; "Trigger a gun" | |