hyponitrous, a. [Pref. hypo- + nitrous.].
Containing or derived from nitrogen having a lower valence than in nitrous compounds. [1913 Webster]
Hyponitrous acid (Chem.)
, an unstable nitrogen acid, NOH, whose salts are produced by reduction of the nitrates, although the acid itself is not isolated in the free state except as a solution in water; -- called also nitrosylic acid.