Definition of rubidium in English:



  • [mass noun] The chemical element of atomic number 37, a rare soft silvery reactive metal of the alkali metal group.

    • ‘The ratio of the amount of the element produced to rubidium remaining in the sample is one of the methods that is being used by geologists to determine the age of the rocks of the Earth.’
    • ‘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.’
    • ‘Elements such as rubidium, zirconium, and aluminum are mostly incorporated into human biochemistry as a consequence of their association with essential elements present in the human diet.’
    • ‘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 mapped the patterns made by known elements and discovered many new ones, including rubidium and cesium.’
    • ‘Cesium and rubidium lose their valence electrons especially easily when light strikes their polished surfaces and are photosensitive over the full visible spectrum.’


Mid 19th century: modern Latin, from Latin rubidus red (with reference to its spectral lines).