timekeeper

plural timekeepers · alternative time-keeper

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. hobbiesA person who records the time elapsed in a sporting event.

   Synonyms: timer

4. entertainmentThe 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. usuallyA 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