1. (noun)niobium, Nb, atomic number 41 a soft grey ductile metallic element used in alloys; occurs in niobite; formerly called columbium Synonyms: atomic number 41, niobium, nota bene
2. (noun)nota bene, NB, N.B. a Latin phrase (or its abbreviation) used to indicate that special attention should be paid to something Synonyms: atomic number 41, niobium, nota bene