time-keeper

Noun

timekeeper (plural timekeepers)

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 premiums for a better time-keeper than any then in use.1878 March 30, Ralph Waldo Emerson, Fortune of the Republic. Lecture Delivered at the Old South Church, March 30, 1878, Boston, Mass.: Houghton, Osgood and Company […], published 1878, →OCLC, page 1

   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 Phenomenology of Musical Experience, Wesleyan University Press, →ISBN, page 152
5. (usually) 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 Illustrated, page 217