nīˈōbēəm noun
( -s )
Etymology: New Latin, from Niobe, daughter of Tantalus + New Latin -ium — so called from its occurrence in tantalite
: a platinum-gray ductile chiefly pentavalent metallic element of brilliant luster that occurs combined in columbite and various other rare minerals but almost always associated with tantalum which it closely resembles chemically and from which it is separated as a by-product and that is used especially in alloys (as in small amounts in stainless steels to inhibit intergranular corrosion) — called also columbium ; symbol Nb ; see element table