'Pyrogallol' definitions:

Definition of 'pyrogallol'

noun

A toxic white lustrous crystalline phenol used to treat certain skin diseases and as a photographic developer [syn: pyrogallol, pyrogallic acid]

From: GCIDE

Pyrogallol \Pyr`o*gal"lol\, n. [Pyrogallic + -ol.] (Chem.) 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. [1913 Webster]