hair trigger

• 形容极易被触发或反应极快的状态，既指人脾气暴躁、一点就着，也指装置或机制稍微一碰就会启动。

A very small or slight provocation that causes a strong reaction, often used to describe someone's temper or a mechanism that responds extremely quickly.

1. Quick to reactC1informal

   A situation or person that reacts extremely quickly and often aggressively to the slightest provocation.

   一触即发

   • He has a hair-trigger temper; any small comment sets him off.
   • The security system has a hair trigger, so even a small movement activates the alarm.
   • Her hair-trigger response to criticism made her difficult to work with.

2. Highly sensitive mechanismC1formal

   A mechanical or electronic device that is set to activate with minimal pressure or input.

   灵敏触发装置

   • The gun's hair trigger made it dangerous to handle.
   • The bomb had a hair trigger, requiring extreme caution during disarming.
   • Engineers designed the sensor with a hair trigger for precise detection.