StyphnicStyph"nic\, a. [Gr. (spurious) sty`fein to contract.] (Chem.) Pertaining to, or designating, a yellow crystalline astringent acid, (NO2)3.C6H.(OH)2, obtained by the action of nitric acid on resorcin. Styphnic acid resembles picric acid, but is not bitter. It acts like a strong dibasic acid, having a series of well defined salts.