atomic number 21 is a noun meaning "a white trivalent metallic element; sometimes classified in the rare earth group; occurs in the Scandinavian mineral thortveitite". It carries one recorded sense.
a white trivalent metallic element; sometimes classified in the rare earth group; occurs in the Scandinavian mineral thortveitite
Definitions, synonyms and semantic relations for atomic number 21 come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.