atomic number 18 is a noun meaning "a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere". It carries one recorded sense.
a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere
Definitions, synonyms and semantic relations for atomic number 18 come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.