(idiomatic) A shockingly unattractive face. / (idiomatic) A shockingly attractive face.

plural of face that would stop a clock

an atomic clock which uses the 1.4 GHz transition in a hydrogen atom to measure time to within 0.45 nanoseconds over a span of 12 hours

A normally unreliable person or instrument can occasionally provide correct information, even if only by accident.

Alternative form of a stopped clock is right twice a day

(neologism, rare, derogatory) A time-waster.

A spring in a mechanical clock.

plural of clockspring

plural of clocksucker

(astronomy) A bright star with precisely known right ascension, used for determining the error of clocks used to time meridian transits