leopard - The Leopard (Panthera pardus) is one of the four big cats of the genus Panthera. Originally, it was thought that a leopard was a hybrid between a lion and a panther, and the leopard's common name derives from this belief; leo is the Greek and Latin word for lion (Greek leon) and pard is an old term meaning panther. In fact, a 'panther' can be any of several species of large felid. In North America, panther means Cougar and in South America a panther is a jaguar. Elsewhere in the world a panther is a leopard. Early naturalists distinguished between leopards and panthers not by colour (a common misconception), but by the length of the tail - panthers having longer tails than leopards.