n.[C]

1. （枪炮的）扳机；触发器
   He pulled the trigger and the bottle was shot to pieces.

   他扣动扳机，瓶子当即被打得粉碎。

2. 起动装置；扳柄；闸柄
3. 能引起反应的刺激物[（+for）]
   Some people say that violent movies are potential triggers for juvenile delinquency.

   一些人说暴力影片可能引起青少年犯罪。

vt.

1. 扣扳机开（枪）；发射
2. 触发，引起[（+off）]
   His action has triggered off a crisis.

   他的行动已经引起一场危机。

   A spark triggered the explosion.

   一粒火星引起了这场爆炸。

vi.

1. 松开扳柄（或闸柄等）

n.

1. a device that releases a spring or catch and so sets off a mechanism, especially in order to fire a gun.
2. an event that causes something to happen.

v.

1. cause (a device) to function.
2. (also trigger something off) cause to happen or exist.