What is "styphnic acid"

n. (context chemistry English) a nitro substituted di-phenol, 2,4,6-trinitrobenzene-1,3-diol, used in the manufacture of dyes, explosives etc

Styphnic acid, or 2,4,6-trinitro-1,3-benzenediol, is a yellow astringent acid that forms hexagonal crystals. It is used in the manufacture of dyes, pigments, inks, medicines, and explosives such as lead styphnate. It is itself a low sensitivity explosive, similar to picric acid, but explodes upon rapid heating.