Pachydermata (from two Greek words παχύς pachys, "thick" and δερμα derma, "skin", meaning 'thick skin') is an obsolete order of mammals described by Gottlieb Storr, Georges Cuvier and others, at one time recognized by many systematists. Because it is polyphyletic, the order is no longer in use, but it is important in the history of systematics. Outside strict biological classification, the term "pachyderm" remains commonly used to describe elephants, rhinoceroses, and hippopotamuses.