Despite its size, it is not typically classified among the "big cats", as it cannot roar, lacking the specialized larynx and hyoid apparatus of Panthera.

Cougars sometimes voice low-pitched hisses, growls, and purrs, as well as chirps and whistles, many of which are comparable to those of domestic cats.

Cougars can be almost as large as jaguars, but are less muscular and not as powerfully built; where their ranges overlap, the cougar tends to be smaller on average.

The cougar is on average larger than all felids apart from lions, tigers, and jaguars.

It has five retractable claws on its forepaws (one a dewclaw) and four on its hind paws.

The larger front feet and claws are adaptations to clutching prey.

Taxonomic research on felids remains partial, and much of what is known about their evolutionary history is based on mitochondrial DNA analysis, and significant confidence intervals exist with suggested dates. The cheetah lineage is suggested by some studies to have diverged from the Puma lineage in the Americas (see American cheetah) and migrated back to Asia and Africa, A high level of genetic similarity has been found among North American cougar populations, suggesting they are all fairly recent descendants of a small ancestral group. propose the original North American population of P.concolor was extirpated during the Pleistocene extinctions some 10,000 years ago, when other large mammals, such as Smilodon, also disappeared.

In the latest genomic study of the Felidae, the common ancestor of today's Leopardus, Lynx, Puma, Prionailurus, and Felis lineages migrated across the Bering land bridge into the Americas 8.0 to 8.5 million years ago (Mya). North America was then repopulated by a group of South American cougars.

The cougar is an ambush predator and pursues a wide variety of prey.

Primary food sources are ungulates, particularly deer, but also livestock.

The head of the cat is round and the ears are erect.

Its powerful forequarters, neck, and jaw serve to grasp and hold large prey.

Adult males are around 2.4 m (7.9 ft) long from nose to tail tip, and females average 2.05 m (6.7 ft), with overall ranges between 1.50 to 2.75 m (4.9 to 9.0 ft) nose to tail suggested for the species in general.