|pər, |per+...- noun
Etymology: International Scientific Vocabulary per- + sulfuric; probably originally formed as French persulphurique
: either of two peroxy acids of sulfur:
a. : a crystalline strongly oxidizing acid H 2 S 2 O 8 obtained usually by electrolysis of sulfuric acid and used chiefly in making hydrogen peroxide and in the form of salts — called also peroxydisulfuric acid; not used systematically
b. : permonosulfuric acid