Hyponitrous /(?)/

Hy·po·ni·trous

Hyponitrous

a.
  1. Containing or derived from nitrogen having a lower valence than in nitrous compounds. (Chem.)

Phrases & Compounds
Hyponitrous acid
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.