Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun atomic_number_18

1 sense of atomic number 18

Sense 1
argon, Ar, atomic number 18 -- (a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere)
       => chemical element, element -- (any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter)
       => noble gas, inert gas, argonon -- (any of the chemically inert gaseous elements of the helium group in the periodic table)