timer

Etymology 1

time (verb) + -er

noun

1. Agent noun of time">time: someone or something that times.
   1. A device used to measure amounts of time">time.
      start the timer when you hear the gunshot
   2. Any electronic function that causes a device to be able to do something automatically after a preset amount of time">time.
   3. A person who records the time">time elapsed in a sporting event.

Etymology 2

time (noun) + -er (measurement suffix) or + -er (occupational suffix)

noun

1. One who has done something a certain number of times.
   third-timer
2. One characterized by a certain time or time frame, such as their work hours.