cesium

noun ce·si·um \ ˈsē-zē-əm also -zhē- \

|Updated on: 22 Jun 2018

Definition of cesium

: a silver-white soft ductile element of the alkali metal group that is the most electropositive element known and that is used especially in photoelectric cells — see Chemical Elements Table

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Recent Examples of cesium from the Web

The particles grab on to ions of cesium, strontium, and other dangerous isotopes in the water, making room for them by spitting out sodium.

— vince beiser, WIRED, "Fukushima’s Other Big Problem: A Million Tons of Radioactive Water," 27 Apr. 2018
The Harvard chemist takes two individual atoms, a sodium and a cesium, each about 10,000 times smaller than a bacterium.

— sophia chen, WIRED, "Chemists Orchestrate the Molecular Union of Two Single Atoms," 27 Apr. 2018
Lasers are used to slow and cool the atoms to near absolute zero, and then more lasers are used to elevate the ball of cesium up the chamber.

— jay bennett, Popular Mechanics, "The Centuries-Long Quest to Measure One Second," 24 Mar. 2017
The calibration is done with the alkali metal cesium.

— jay bennett, Popular Mechanics, "The Centuries-Long Quest to Measure One Second," 24 Mar. 2017
The concentrations of radioactive cesium near Japan, for example, were much higher than the concentrations along the west coast of the US.

— rachel becker, The Verge, "Katsuko Saruhashi turned radioactive fallout into a scientific legacy," 22 Mar. 2018
A few months after that incident, in Tokyo, a protester was arrested for landing a drone carrying a harmless amount of radioactive cesium on the prime minister’s office.

— michael laris, Washington Post, "Drones keep entering no-fly zones over Washington, raising security concerns," 13 Jan. 2018
After preliminary measurements are completed, the physicists plan to install a low-temperature cesium iodide detector to search for dark matter.

— pallava bagla, Science | AAAS, "India joins hunt for dark matter," 31 Aug. 2017
The Chinese clock, however, is less advanced than its European counterpart, which will use cold cesium atoms.

— edwin cartlidge, Science | AAAS, "China’s atomic clock passes space test," 20 Sep. 2017

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Origin and Etymology of cesium

New Latin, from Latin caesius bluish gray

NEW! Time Traveler

First Known Use: 1861

in the meaning defined above

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Medical Dictionary

cesium

noun ce·si·um

variants: or chiefly British caesium play \ˈsē-zē-əm\

medical Definition of cesium

: a silver-white soft ductile element of the alkali metal group that is the most electropositive element known and that is used especially in photoelectric cells —symbol Cs — see Chemical Elements Table