·noun A phenol metameric with phloroglucin, obtained by the distillation of gallic acid as a poisonous white crystalline substance having acid properties, and hence called also pyrogallic acid. It is a strong reducer, and is used as a developer in photography and in the production of certain dyes.
Pyrogallol is an organic compound with the formula C6H3(OH)3. It is a water-soluble, white solid although samples are typically brownish because of its sensitivity toward oxygen. It is one of three isomers of benzenetriols.