Definition of cesium in English:


(British caesium)


  • The chemical element of atomic number 55, a soft, silvery, extremely reactive metal. It belongs to the alkali metal group and occurs as a trace element in some rocks and minerals.

    • ‘Those that produce a measurable spectrum when subjected to flame include, but are not limited to, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, and cadmium.’
    • ‘They discovered two new elements, caesium and rubidium in the course of their investigations.’
    • ‘Fifteen years after the disaster, Bulgaria still suffers from the effects - mostly in the form of increased levels in the environment of cesium and strontium.’
    • ‘However, water-soluble rubidium, cesium, thallium, and silver minerals are virtually nonexistent and should pose no complication.’
    • ‘Researchers are particularly interested in zeolites filled with metal atoms such as cesium.’
    • ‘These elements - lithium, sodium, potassium, rubidium, cesium and francium - all react with water to give solutions that change the color of a vegetable dye from red to blue.’
    • ‘They also can form condensates out of numerous different elements, including sodium, potassium, lithium, cesium, hydrogen and helium.’
    • ‘The alkali metals are silver colored except for cesium, which is pale gold.’
    • ‘Once ingested, radioactive plutonium, cesium and strontium atoms morph into agents of death in the body, stealthily emitting radiation internally and constantly bombarding the genes of nearby cells.’
    • ‘Reasonable permeation free energy profiles are obtained for potassium, rubidium, and cesium; binding wells are shallow and the central barrier is small.’
    • ‘In addition to this, the government-sponsored nuclear industry regularly released enormous quantities of radioactive Iodine, cesium, and strontium into the atmosphere just to see what might happen.’
    • ‘While cesium and strontium, the two materials found in the generators, cannot be used to make nuclear weapons, they could contaminate large areas if combined with explosives.’
    • ‘They mapped the patterns made by known elements and discovered many new ones, including rubidium and cesium.’
    • ‘Later, the radioactive cesium or strontium is trapped in the zeolite and is excreted.’
    • ‘The same cannot be said of logarithms or the reactivity of caesium.’
    • ‘Food irradiation uses gamma rays from cesium - 137 and cobalt - 60, which are capable of causing chemical changes in these foods.’
    • ‘The University of Southampton used mass spectrometry to probe samples for plutonium, radium and caesium.’
    • ‘We're using our big laser system to study the detailed atomic physics of xenon with other alkalis besides rubidium, such as cesium and potassium.’
    • ‘We breathe air polluted with lead, carbon monoxide and nitrogen oxides from car exhausts, sulphur dioxide from chimney flues, radioactive iodine, caesium and a host of other radionuclides from the flues of nuclear installations.’
    • ‘Because of the very slow natural process of decontamination of soil tainted by strontium 90, cesium 137, and plutonium, the agricultural consequences will persist for forty to fifty years.’


Mid 19th century: from Latin caesius grayish-blue (because it has characteristic lines in the blue part of the spectrum).