timekeeper

Noun

1. A device that shows the time; a timepiece.
   • The sailors sail by chronometers that do not lose two or three seconds in a year, ever since [Isaac] Newton explained to Parliament that the way to improve navigation was to get good watches, and to offer public...

   Synonyms: timepiece clock watch

2. A person who keeps records of the hours of attendance of employees.
3. A person who records the time elapsed in a sporting event.

   Synonyms: timer

4. 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, Harris M. Berger, Metal, Rock, and Jazz: Perception and the...
5. 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 April, Warren Smith, “The problems of train regulation - a study of operation at Trent”, in Trains...