cesium 133


: an isotope of cesium used especially in atomic clocks and one of whose atomic transitions is used as a scientific time standard

Example Sentences

Recent Examples on the Web The official length of the basic unit, the second, was fixed at 9,192,631,770 vibrations of an atom of cesium 133. Alanna Mitchell, New York Times, 14 Nov. 2022 But improving upon the cesium 133 atom comes with improvements in our laser capabilities. Tim Newcomb, Popular Mechanics, 26 Apr. 2022 Since 1967, the second has been defined by the cesium 133 atom. Tim Newcomb, Popular Mechanics, 26 Apr. 2022 In the case of cesium 133, the frequency is nearly 9.2 billion ticks per second — 9,192,631,770, to be precise. New York Times, 25 Apr. 2022

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'cesium 133.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

First Known Use

1964, in the meaning defined above

Time Traveler
The first known use of cesium 133 was in 1964

Dictionary Entries Near cesium 133

Cite this Entry

“Cesium 133.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cesium%20133. Accessed 6 Feb. 2023.

Last Updated: - Updated example sentences
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