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Responding to the slightest provocation or stimulation: a hair-trigger temper; a hair-trigger reaction.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

hair′ trig`ger

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


1. easily activated or set off; put into operation by the slightest impulse.
2. reacting immediately to the slightest provocation: a hair-trigger temper.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


- Its underlying meaning is something that may be triggered with the pressure of something as slight as a hair.
See also related terms for slight.
Farlex Trivia Dictionary. © 2012 Farlex, Inc. All rights reserved.


[ˈhɛəˌtrɪgəʳ] ADJ (fig) [temper, reaction] → explosivo
see also hair B
Collins Spanish Dictionary - Complete and Unabridged 8th Edition 2005 © William Collins Sons & Co. Ltd. 1971, 1988 © HarperCollins Publishers 1992, 1993, 1996, 1997, 2000, 2003, 2005
References in classic literature ?
"My nerves are on a hair-trigger these days," Martin apologized.
The inmates were asleep, but it was a sleep that was set on a hair-trigger, on account of the exciting episode of the night.
I have always held, too, that pistol practice should be distinctly an open-air pastime; and when Holmes, in one of his queer humors, would sit in an arm-chair with his hair-trigger and a hundred Boxer cartridges, and proceed to adorn the opposite wall with a patriotic V.
A thug with a hair-trigger temper has been locked up for more than four years after savagely beating up a pizza delivery driver in a random attack because he was 'frustrated'.
GAZA: Schools reopened in southern Israel and traffic-clogged Gaza's streets on Wednesday in signs of a pullback from the most serious escalation of cross-border fighting in months.But while violence eased amid Egyptian mediation, Israeli forces and Palestinian militants were on a hair-trigger footing, with rocket attacks from Gaza and Israeli air strikes in the enclave briefly resuming late on Tuesday after a day-long lull.
Since the cold war, the United States has kept 900 nuclear weapons on hair-trigger alert, enabling the president to order a strike in 10 minutes.
TYRRELL HATTON has vowed to grow up and shackle the hair-trigger temper that makes him cringe.
The new Elite controller is said to have a three-stage hair trigger lock, allowing you to adjust the depression of the hair-trigger more than it was previously possible.
There are many steps that can be taken like running a campaign that asks Russia and the US to cease putting their arsenal on hair-trigger alert.
I just hope they can put their macho posturing and hair-trigger tempers to one side and act like grown-ups for once.
Emmerdale Mon-Fri, UTV He's always been a bit of a loose cannon with a hair-trigger temper, but now Lachlan White has completely lost the plot.
By his inflammatory rhetoric regarding North Korea, Trump intends "to create the hair-trigger situation on the peninsula and shovel up money by selling the US-made arms and equipment to vassal forces," the commentary read, referring to Japan and South Korea, which the North Korean outlet called "puppets" of Washington.