largest New World member of the cat (feline) family (Felidae), once found from the U.S.-Mexican border southward to Patagonia, Argentina. Its preferred habitats are usually swamps and wooded regions, but jaguars also live in scrublands and deserts. The jaguar is virtually extinct in the northern part of its original range and survives in reduced numbers only in remote areas of Central and South America; the largest known population exists in the Amazon rainforest.

Jaguars are also larger and more heavily built than leopards. The male jaguar, which is generally larger than the female, attains a length of 1.7–2.7 metres (5.6–9 feet), including the 0.6–0.9-metre (2–3-foot) tail, with a shoulder height of 0.7–0.8 metre (2.3–2.6 feet); it weighs from 100 to 160 kg (220 to 350 pounds). The jaguars of South America are largest.

A solitary predator, the jaguar is a stalk-and-ambush hunter; its name comes from the Indian word yaguar, meaning “he who kills with one leap.” Jaguars are swift and agile and are very good climbers. They enter water freely and appear to enjoy bathing. Although active during the day, jaguars hunt mainly at night and on the ground. capybara and peccary are their preferred prey, but they will also take deer, birds, crocodilians, and fish. Livestock are occasionally attacked in areas where ranches have replaced natural habitat. The cat is a savage fighter when cornered but does not normally attack humans.

Jaguars adhere to a land tenure system much like cougars and tigers (tiger). Females establish overlapping home ranges, and female offspring may inherit land from their mothers. Males establish territories twice as large as females and overlap the ranges of several females. Both sexes mark their ranges with urine. Northern populations mate toward the end of the year, but in the tropics mating activity seems not to be restricted to a particular breeding season. After a gestation period of about 100 days, the female bears one to four tiny spotted cubs weighing 100–900 grams (less than 2 pounds) that do not open their eyes for 13 days. The mother raises the young for approximately two years. Full size and sexual maturity are reached at three to four years.

The jaguar is grouped along with lions and tigers with the big, or roaring, cats and is the only such cat in the Western Hemisphere. The jaguar's sound repertoire includes snarls, growls, and deep, hoarse grunts.