Webster's Revised Unabridged Dictionary · 1913

Hyponitrous

Hyponitrous , adjective

[Prefix hypo- + nitrous.]

(Chemistry) Containing or derived from nitrogen having a lower valence than in nitrous compounds.
Collocations (1)
Hyponitrous acid (Chemistry) , 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.