The terms big cat and great cat, while not a biological classification, are used informally to distinguish the larger felid species from smaller ones. A narrower definition of includes five members of the genus Panthera: the tiger, lion, jaguar, leopard, and snow leopard. Only members of this genus are able to roar. A more expansive definition additionally includes the cougar and cheetah. Another cat, the clouded leopard is considered an evolutionary link between big and small cats.