atomic clock

highly accurate electronic clock regulated by the vibration frequencies of particular atoms or molecules

An Atomic Clock is a type of clock that uses an atomic resonance frequency standard to feed its counter. Early atomic clocks were masers with attached equipment. Today's best atomic frequency standards (or clocks) are based on absorption spectroscopy of cold atoms in atomic fountains. National standards agencies maintain an accuracy of 10-9 seconds per day (approximately 1 part in 1014), and a precision equal to the frequency of the radio transmitter pumping the maser. The clocks maintain a continuous and stable time scale, International Atomic Time (TAI). For civil time, another time scale is disseminated, Coordinated Universal Time (UTC). UTC is derived from TAI, but synchronized with the passing of day and night based on astronomical observations.
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Noun
1. a timepiece that derives its time scale from the vibration of atoms or molecules
(hypernym) timepiece, timekeeper
(hyponym) ammonia clock

atomic clock
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OROLOGIO ATOMICO