timekeeper - a measuring instrument or device for keeping timeatomic clock - a timepiece that derives its time scale from the vibration of atoms or molecules balance wheel, balance - a wheel that regulates the rate of movement in a machine; especially a wheel oscillating against the hairspring of a timepiece to regulate its beat clock - a timepiece that shows the time of day dial - the face of a timepiece; graduated to show the hours escapement - mechanical device that regulates movement hairspring - a fine spiral spring that regulates the movement of the balance wheel in a timepiece hand - a rotating pointer on the face of a timepiece; "the big hand counts the minutes" sandglass - timepiece in which the passage of time is indicated by the flow of sand from one transparent container to another through a narrow passage sundial - timepiece that indicates the daylight hours by the shadow that the gnomon casts on a calibrated dial time-ball - a ball that slides down a staff to show a fixed time; especially at an observatory timer - a timepiece that measures a time interval and signals its end |