atomic 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"

measuring device, measuring instrument, measuring system - instrument that shows the extent or amount or quantity or degree of something

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

watch, ticker - a small portable timepiece