\Ar"gon\, n. [Gr. ? inactive.] (Chem.)
A substance regarded as an element, contained in the
atmosphere and remarkable for its chemical inertness.
--Rayleigh and Ramsay.

\Ar"gon\, n. [NL., fr. Gr. ?, neut. of ? inactive; ? priv.
+ ? work.] (Chem.)
A colorless, odorless gas occurring in the air (of which it
constitutes 0.93 per cent by volume), in volcanic gases,
etc.; -- so named on account of its inertness by Rayleigh and
Ramsay, who prepared and examined it in 1894-95. Symbol, A;
at. wt., 39.9. Argon is condensible to a colorless liquid
boiling at -186.1[deg] C. and to a solid melting at
-189.6[deg] C. It has a characteristic spectrum. No compounds
of it are known, but there is physical evidence that its
molecule is monatomic. Weight of one liter at 0[deg] C. and
760 mm., 1.7828 g.