nitrous acid
Chemical term for HNO₂. Used in chemistry and related fields.
Nitrous acid is an unstable compound that exists only in aqueous solution.
亜硝酸塩 is a nitrite salt, derived from nitrous acid.
Compound of 亜 (a-, 'sub-') and 硝酸 (shōsan, 'nitric acid'), indicating a lower oxidation state than nitric acid.