noun a substance regarded as an element, contained in the atmosphere and remarkable for its chemical inertness.
2. argon ·add. ·noun 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° c. and to a solid melting at -189.6° 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° c. and 760 mm., 1.7828 g.