1838, from French pachyderme (c.1600), adopted as a biological term 1797 by French naturalist Georges Léopole Chrétien Frédéric Dagobert, Baron Cuvier (1769-1832), from Greek pachydermos "thick-skinned," from pachys "thick, large, massive," from PIE *bhengh- "thick, fat" (cognates: Sanskrit bahu- "much, numerous" Avestan bazah- "height, depth," Hittite pankush "large," Old Norse bingr "heap," Old High German bungo "a bulb," Lithuanian biess "thick") + derma "skin" (see derma).