Timer (noun)

A device used to measure a specified amount of time, often used to control other devices.

Origin:

Derived from the word 'time' and a variant of the word 'rime' meaning 'a device that measures time'.

Examples:

1. She set a timer for 30 minutes to remind herself to take a break.
2. The timer on the oven beeped when the cookies were ready.
3. The game had a timer that counted down from 60 seconds.
4. The water heater had a timer to automatically turn off after 4 hours.
5. The doctor used a timer to measure the speed of the patient's heart rate.