trigger

American  

[trig-er] / ˈtrɪg ər /

noun

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 catch 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. something that evokes the memory of a traumatic experience, setting off an intense negative emotional reaction.

   This issue of the magazine contains accounts of sexual assault, and may be a trigger for some people.

5. Slang. triggerman.

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verb (used with object)

1. to initiate or precipitate (a chain of events, scientific reaction, psychological process, etc.).

   Their small protest triggered a mass demonstration.

2. to fire or explode (a gun, missile, etc.) by pulling a trigger or releasing a triggering device.

   He accidentally triggered his rifle.

3. to set off a negative emotional reaction in (someone), as by evoking the memory of a traumatic experience, repeatedly raising a sensitive issue, etc..

   I missed seeing my mom in the ICU before she died, and imagining her there triggers me every time I see ICU footage on TV.

verb (used without object)

1. to release a trigger.

2. to become active; activate.

idioms

1. quick on the trigger, quick to act or respond; impetuous; alert.

trigger British  

/ ˈtrɪɡə /

noun

1. a small projecting lever that activates the firing mechanism of a firearm

2. machinery a device that releases a spring-loaded mechanism or a similar arrangement

3. any event that sets a course of action in motion

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verb

1. (usually foll by off) to give rise (to); set off

2. to fire or set in motion by or as by pulling a trigger

trigger More Idioms  

More idioms and phrases containing trigger

• quick on the draw (trigger)

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Other Word Forms

• triggered adjective
• triggerless adjective

Etymology

Origin of trigger

First recorded in 1615–25; earlier tricker, from Dutch trekker, equivalent to trekk(en) “to pull” + -er -er ¹

Explanation

A trigger is a metal lever that when pulled discharges a gun. You shoot the gun by pulling the trigger. Trigger can also mean the start of a process––violent protests might trigger a revolution. Certain scents, places, or old love songs can be said to trigger, or activate, memories. If you get weepy when you hear the national anthem, that may be because it triggers thoughts of family, home, baseball and the Fourth of July. For someone in frail health, a seemingly minor problem like getting a common cold, might trigger a series of physical responses that end up landing them in the hospital.

Example Sentences

They found that certain bacterial sugars can trigger immune reactions that kill brain cells, and importantly, they also identified ways to stop this process.

From Science Daily • Apr. 9, 2026

The acquisition is expected to trigger substantial layoffs and other cost-cuts as the new owners consolidate two legendary studios and TV operations, including dozens of cable channels.

From Los Angeles Times • Apr. 9, 2026

It was unable to do that in January and February this year as both were above the trigger intramonth, but unable to finish above it.

From Barron's • Apr. 9, 2026

That’s because the mood on Wall Street in March and early April hasn’t been pessimistic enough to trigger a contrarian buy signal.

From MarketWatch • Apr. 9, 2026

The sheriff looked the gun o’er, seent it didn’t have no bullets and that the trigger was so rusty it wouldn’t budge.

From "The Journey of Little Charlie" by Christopher Paul Curtis

Related Words

• bring about
• cause
• generate
• produce
• prompt
• provoke
• set off
• spark
• start