A peroxy acid (often spelled as one word, peroxyacid, and sometimes called peracid) is an acid which contains an acidic -OOH group. The two main classes are those derived from conventional mineral acids, especially sulfuric acid, and the organic derivatives of carboxylic acids. They are generally strong oxidizers.
Read more about Peroxy Acid: Inorganic Peroxy Acids, Organic Peracids