(Science: chemistry, element) 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. Specific gravity 12.26. See Platinum metals, under Platinum.
atomic weight: 103.5
Origin: NL. So named from the Ruthenians, a Little Russian people, as coming from Russia, the metal having been found in the Ural mountains.