hair trigger

¹ American  

noun

1. a trigger that allows the firing mechanism of a firearm to be operated by very slight pressure.

---

hair-trigger ² American  

[hair-trig-er] / ˈhɛərˌtrɪg ər /

adjective

1. easily activated or set off; reacting immediately to the slightest provocation or cause.

   a hair-trigger temper.

---

hair trigger British  

noun

1. a trigger of a firearm that responds to very slight pressure

2. informal

   1. any mechanism, reaction, etc, set in operation by slight provocation

   2. ( as modifier )

      a hair-trigger temper

---

Etymology

Origin of hair trigger¹

First recorded in 1815–25

Origin of hair-trigger²

First recorded in 1885–90

Example Sentences

Years of mismanagement and ill-fated transfers have left Spurs with a jumbled squad and a hair trigger for firing coaches.

From The Wall Street Journal • Mar. 14, 2026

Investors appear to have been on hair trigger.

From Barron's • Dec. 22, 2025

In theory, the hair trigger gets shots off faster when playing shooters, and the rear paddles allow you to jump, crouch, reload, etc., without taking your thumb off the right stick for aiming.

From The Verge • May 25, 2022

He’s in a stage in his career when he’s on a hair trigger to tuck the ball and run.

From Los Angeles Times • Oct. 5, 2021

His sense of right and wrong had been mounted on a hair trigger.

From "Friday Night Lights: A Town, A Team, And A Dream" by H.G. Bissinger

Related Words

• critical
• precarious
• sensitive
• ticklish
• touchy
• tricky
• unpredictable
• volatile