Orangutan, a species of anthropoid (manlike) ape. Orangutans are related to gorillas, chimpanzees, and gibbons. They are found in tropical rain forests of the islands of Sumatra and Borneo. (Their name comes from the Malayan for "man of the woods.")

An adult male is about 4 feet (1.4 m) tall when standing erect, and weighs up to 200 pounds (90 kg). The female is smaller and weighs about 90 pounds (40 kg). The orangutan has a sloping forehead; small, rounded ears; a short, stout body; and short legs. It has no tail. It is covered with red or reddish-brown brown shaggy hair. There are bald patches on the forehead and shoulders, and around the mouth. Old males have protruding areas of skin on their cheeks, which make their faces appear broad.

The orangutanThe orangutan has long arms, small ears, a stout body, and short legs.

Orangutans spend most of their lives in trees. They use their long, powerful arms to swing from one branch to another. Their thumbs and big toes are opposable, allowing them to grasp things with their hands and feet. Orangutans feed mainly on fruit, insects, and leaves. At night they gather leaves and twigs and build a large platform-like nest on which they sleep. Orangutans typically live alone or in small groups. The female gives birth to a single offspring after a gestation period of eight to nine months. The young orangutan is carried on the mother's back for about a year. It is usually weaned after two years. Orangutans reach sexual maturity at the age of seven or eight. Their average life span is 30 years.

Due to commercial logging and illegal hunting, the orangutan is an endangered species.

The orangutan is Pongo pygmaeus of the great ape family, Pongidae.