hair-trigger
UK[ˈheəˌtrɪɡə]US[ˈhɛrˌtrɪɡər]
adj
Reacting immediately and very easily to a slight cause
n
A trigger that responds to the slightest pressure
Morpheme Breakdown
hair
trigger
hair
trigger
that which pulls
Etymology
The term 'hair-trigger' originated in the early 19th century from the world of firearms, describing a gun trigger adjusted to release with the slightest pressure, comparable to the weight of a single hair. The compound leverages 'hair' as a powerful metaphor for extreme sensitivity and fineness, a usage also seen in terms like 'hairline' and 'hair-splitting'. Over time, this literal descriptor evolved into a widely used adjective, applying to anything—from a person's temper to a political situation—that is set to react explosively to the most minor stimulus. This evolution perfectly illustrates how a technical term from a specific craft can migrate into general language, carrying its vivid imagery to describe abstract states of readiness and volatility.
Analysis
Structure: hair + trigger
- hair: From Old English 'hær', meaning a single filament or the collective mass of filaments growing from the skin. In this compound, it functions as a metaphorical intensifier denoting extreme fineness or sensitivity.
- trigger: From Dutch 'trekker', meaning 'that which pulls'. It functions as the core noun, referring to the lever that releases a mechanism, especially on a firearm.
Examples
He has a hair-trigger temper, so be careful what you say around him.
The negotiations were at a hair-trigger stage, with any minor incident capable of causing a breakdown.
The old pistol was fitted with a dangerous hair-trigger.