timekeeper

noun5

1. •
   A person who keeps records of the hours of attendance of employees.
2. •
   A person who records the time elapsed in a sporting event.
3. •
   A device that shows the time; a timepiece.
4. •
   A person (or something controlled by a person) that is punctual.

   • As it happens, the Leicester–Beeston train is quite a good timekeeper—it sometimes runs a few minutes early— […] — 1961
5. •
   The group member who controls the rhythm of the music when a group of musicians play together.

   • There was no consensus among jazz musicians about who was the primary timekeeper in a jazz band; some said the drummers and others said the bassist. — 2011