The diverse order Carnivora (pron.: // or //; from Latin carō (stem carn-) "flesh", + vorāre "to devour") includes over 280 species of placental mammals. Its members are formally referred to as carnivorans, whereas the word "carnivore" (often popularly applied to members of this group) can refer to any meat-eating organism. Carnivorans are the most diverse in size of any mammalian order, ranging from the least weasel (Mustela nivalis), at as little as 25 g (0.88 oz) and 11 cm (4.3 in), to the polar bear (Ursus maritimus), which can weigh up to 1,000 kg (2,200 lb), to the southern elephant seal (Mirounga leonina), whose adult males weigh up to 5,000 kg (11,000 lb) and measure up to 6.9 m (23 ft) in length.
Panthera is a genus of the family Felidae (cats), which contains four well-known living species: the tiger, the lion, the jaguar, and the leopard. The genus comprises about half of the Pantherinae subfamily, the big cats. The word "panther", while technically referring to all members of the genus, is commonly used to specifically designate the black panther, a melanistic jaguar or leopard, and the Florida panther, a subspecies of cougar (Puma concolor coryi).
Only the four Panthera cat species have the anatomical structure that enables them to roar. The primary reason for this was formerly assumed to be the incomplete ossification of the hyoid bone. However, new studies show the ability to roar is due to other morphological features, especially of the larynx. The snow leopard, Uncia uncia, which is sometimes included within Panthera, does not roar. Although it has an incomplete ossification of the hyoid bone, it lacks the special morphology of the larynx.
However, due to more recent genetic studies, the snow leopard is now becoming more generally considered as Panthera uncia and is presently classified as such by IUCN.