Simple Definition of timer
: a special watch that is used to measure the amount of time that is taken to finish a race, a test, etc.; also : a person who uses such a watch to time someone or something
: a device that makes a sound when a certain amount of time has passed
: a device that can be set to turn something (such as a light) on or off at a certain time
Examples of timer in a sentence
He was the official timer for the race.
She set the timer on the oven for one hour.
The timer is set to go off in 15 minutes.
First Known Use of timer
Seen and Heard
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