HyperDic: ammonia_clock

English > 1 sense of the expression *ammonia clock*:
NOUN	artifact	ammonia clock	an atomic clock based on vibrational frequency of the nitrogen atom in the ammonia molecule

English > *ammonia clock*: 1 sense > noun 1, artifact
Meaning	An atomic clock based on vibrational frequency of the nitrogen atom in the ammonia molecule.
Broader	atomic clock	A timepiece that derives its time scale from the vibration of atoms or molecules