timer
noun [ C ] uk/ˈtaɪ.mər/ us/ˈtaɪ.mɚ/
定时器;计时器
a device that makes a sound when a particular number of minutes, hours, etc. have gone past
He set the timer on the oven to/for 20 minutes (= to record when 20 minutes had gone past). 他给烤箱定时器定了20分钟。
(UK also time switch)计时开关，定时开关
a device on a machine that causes the machine to start or stop working at a particular point in the day