- a ductile white superconductive metallic element that occurs principally in columbite and tantalite: used in steel alloys. Symbol: Nb; atomic no: 41; atomic wt: 92.90638; valency: 2, 3, or 5; relative density: 8.57; melting pt: 2469±10°C; boiling pt: 4744°CFormer name: columbium
WordReference Random House Unabridged Dictionary of American English © 2026
ni•o•bi•um
(nī ō′bē əm),USA pronunciation n. [Chem.]
- a steel-gray metallic element resembling tantalum in its chemical properties;
becomes a superconductor below 9 K;
used chiefly in alloy steels. Symbol: Nb;
at. no.: 41;
at. wt.: 92.906;
sp. gr.: 8.4 at 20°C.
- Neo-Latin; see Niobe, -ium
- 1835–45
Collins Concise English Dictionary © HarperCollins Publishers::
niobium /naɪˈəʊbɪəm/ n
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