'Monatomic' definitions:

Definition of 'monatomic'

From: WordNet
adjective
Of or relating to an element consisting of a single atom; "helium and argon are monatomic gases" [syn: monatomic, monoatomic]

Definition of 'Monatomic'

From: GCIDE
  • Monatomic \Mon`a*tom"ic\, adv. [Mon- + atomic.] (Chem.) (a) Consisting of, or containing, one atom; as, the molecule of mercury is monatomic. (b) Having the equivalence or replacing power of an atom of hydrogen; univalent; as, the methyl radical is monatomic. [1913 Webster]