Nb

Từ điển WordNet v3.1 - WordNet Dictionary

noun

a soft grey ductile metallic element used in alloys;
occurs in niobite;
formerly called columbium
• Syn:
niobium, atomic number 41
• Hypernyms:
metallic element, metal
• Hyponyms:
columbium
• Substance Holonyms:
niobite, columbite