Function: noun
Date: 1966
: an isotope of cesium used especially in atomic clocks and one of whose atomic transitions is used as a scientific time standard
Function: noun
Date: 1966
: an isotope of cesium used especially in atomic clocks and one of whose atomic transitions is used as a scientific time standard
Merriam Webster Collegiate English Dictionary. Merriam Webster - Энциклопедический словарь английского языка. 2012