an unstable inorganic acid known only in solution and as nitrite salts
Nitrous acid (HNO2). A weak acid that exists only in solution. It can form water-soluble nitrites and stable esters. (From Merck Index, 11th ed)
An uncertain acid.
A monobasic acid, HNO2, known only in an unstable aqueous solution, prepared by dissolving nitrogen trioxid in water. Its salts are the nitrites.