D defs.my
Entry 1 sense Webster, 1913

Ruthenium

/ro͞o-thē′-nē-əm/ · Ru·the·ni·um · IPA /ɹuːˈθiːniəm/
01 n. A rare element of the light platinum group, found associated with platinum ores, and isolated as a hard, brittle steel-gray metal which is …
  1. 1.
    A rare element of the light platinum group, found associated with platinum ores, and isolated as a hard, brittle steel-gray metal which is very infusible. Symbol Ru. Atomic weight 103.5. Specific gravity 12.26. See Platinum metals, under Platinum.(Chem.) See: Platinum