\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.