a. [ Pref. hypo- + nitrous. ] (Chem.) Containing or derived from nitrogen having a lower valence than in nitrous compounds. [ 1913 Webster ]
Hyponitrous acid (Chem.),
a. [ L. nitrosus full of natron: cf. F. nitreux. See Niter. ]
Nitrous acid (Chem.),
Nitrous oxide.