Definition of americium in English:



  • [mass noun] The chemical element of atomic number 95, a radioactive metal of the actinide series. Americium does not occur naturally and was first made by bombarding plutonium with neutrons.

    • ‘Internal contamination with plutonium, americium, or curium can occur through a variety of routes including ingestion, inhalation, or direct contact through wounds.’
    • ‘Kept secret until after the war, they were respectively called americium and curium.’
    • ‘Trace levels of plutonium and americium from nuclear weapons tests in the 1960s can be found in most homes, as can radioactive isotopes of caesium from the Chernobyl accident in 1986.’
    • ‘When americium was used as a target in this research, evidence for the formation of a new element was obtained.’
    • ‘It was the first commercial manufacturer of plutonium and americium neutron sources for oil well, logging and other applications.’


1940s: from America (where it was first made) + -ium.