\In"di*um\, n. [NL. See {Indigo}.] (Chem.)
A rare metallic element, discovered in certain ores of zinc,
by means of its characteristic spectrum of two indigo blue
lines; hence, its name. In appearance it resembles zinc,
being white or lead gray, soft, malleable and easily fusible,
but in its chemical relation it resembles aluminium or
gallium. Symbol In. Atomic weight, 113.4.