argon Argolid • Argonaut · · · Info · Definitions · Synonyms · Characters · · argon · · Text Latin · · Script 5 · · Length Definitions · · · (noun) a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere. Synonyms: Ar, atomic number 18. · · Noun Definition 1 Synonyms · · · ar · · Synonym 1 atomic number 18 · · Synonym 2 Characters · · a latin small letter a U+0061 g latin small letter g U+0067 n latin small letter n U+006E o latin small letter o U+006F r latin small letter r U+0072