a colourless crystalline compound obtained from tannin: used as a tanning agent and in making inks, paper, and pyrogallol; 3,4,5-trihydroxybenzoic acid. Formula: C6H2(OH)3COOH
gallic acid in American English
a nearly colorless, crystalline acid, (OH)3C6H2COOH, prepared from tannins, etc. and used in photography and the manufacture of inks, dyes, etc.