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

plural of hydrogen maser atomic clock

plural of face that would stop a clock

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

Alternative form of counterclockwise

Alternative form of counter-clockwise

(US) counterclockwise; anticlockwise

(US) counterclockwise; anticlockwise

In a curve or twist corresponding to the movement of the hands of a clock.