hair-trigger.

So sensitive that a very small stimulus can provoke an immediate response.

Use it for

Words that belong together

• a hair-trigger response
• hair-trigger nerves
• hair-trigger sensitivity

On the page

After the ambush, he developed a hair-trigger startle response.

Her hair-trigger nerves turned each footstep into a warning.

The crowd’s hair-trigger reaction made the steward lower his voice.

Usage notes

Primary category: fear. Not intrinsically fearful: anger and mechanical triggers also qualify. In fear writing, specify a startle or defensive reaction. Normally non-gradable in this sense; degree words describe intensity, not a regular comparison.