Definition of osmium in English:



mass noun
  • The chemical element of atomic number 76, a hard, dense silvery-white metal of the transition series.

    • ‘Other examples of relative isotopic dating are the deuterium variations in ice cores and the osmium isotope record of marine sediments.’
    • ‘With the exception of two of the platinum-group metals, osmium and iridium, they have the highest melting temperatures and lowest vapor pressures of all metals.’
    • ‘Along with osmium and platinum, iridium is one of the densest elements in the periodic table: two cubic feet of it weigh as much as a Buick.’
    • ‘Scientists speculate that the asteroids would probably be very rich in minerals with a very high melting point, such as iron and nickel or rarer metals like tungsten, osmium, and zirconium.’
    • ‘The addition of small amounts of osmium to these metals greatly increases their hardness.’


Early 19th century: modern Latin, from Greek osmē ‘smell’ (from the pungent smell of its tetroxide).