an electric light, usually outside a building, that switches on when someone or something moves near it

Burglars tried to break into the house in the early hours, but they were spotted by vigilant neighbours when security lights came on. 小偷凌晨时分企图破门而入，但安全灯亮起，他们被警惕的邻居发现了。

The animal was seen in a back garden when it set off a security light. 这只动物引亮了安全灯，有人看见它在后花园里。