Breadfruit (Artocarpus altilis) is a species of flowering tree in the mulberry and jackfruit family (Moraceae) believed to have been selectively bred in Polynesia from the breadnut (Artocarpus camansi). Breadfruit was spread into Oceania via the Austronesian expansion and to further tropical areas during the Colonial Era. British and French navigators introduced a few Polynesian seedless varieties to Caribbean islands during the late 18th century.

It is grown in 90 countries throughout South and Southeast Asia, islands in the Pacific Ocean and Caribbean Sea, Central America, and Africa. Its name is derived from the texture of the moderately ripe fruit when cooked, similar to freshly baked bread and having a potato-like flavor.

The trees have been widely planted in tropical regions, including lowland Central America, northern South America, and the Caribbean. In addition to the fruit serving as a staple food in many cultures, the light, sturdy timber of breadfruit has been used for making furniture, houses, and surfboards in the tropics.

Breadfruit is closely related to A. camansi (breadnut or seeded breadfruit) of New Guinea, the Maluku Islands, and the Philippines, A. blancoi (tipolo or antipolo) of the Philippines, and slightly more distantly to A. mariannensis (dugdug) of Micronesia, all of which are sometimes also referred to as "breadfruit". It is also closely related to the jackfruit.

Breadfruit trees grow to a height of 26 m (85 ft). The large and thick leaves are deeply cut into pinnate lobes. All parts of the tree yield latex, which is useful for boat caulking.

The trees are monoecious, with male and female flowers growing on the same tree. The male flowers emerge first, followed shortly afterward by the female flowers. The latter grow into capitula, which are capable of pollination just three days later. Pollination occurs mainly by fruit bats, but cultivated varieties produce fruit without pollination. The compound, false fruit develops from the swollen perianth, and originates from 1,500 to 2,000 flowers visible on the skin of the fruit as hexagon-like disks.

Breadfruit is one of the highest-yielding food plants, with a single tree producing up to 200 or more grapefruit-sized fruits per season, requiring limited care. In the South Pacific, the trees yield 50 to 150 fruits per year, usually round, oval, or oblong, and weighing 0.25 to 6.0 kg (0.55 to 13 lb). Productivity varies between wet and dry areas. Studies in Barbados indicate a reasonable potential of 15 to 30 t/ha (6.7 to 13.4 short ton/acre). The ovoid fruit has a rough surface, and each fruit is divided into many achenes, each surrounded by a fleshy perianth and growing on a fleshy receptacle. Most selectively bred cultivars have seedless fruit, whereas seeded varieties are grown mainly for their edible seeds. Breadfruit is usually propagated using root cuttings.

Breadfruit is closely related to the breadnut. It is similar in appearance to its relative of the same genus, the jackfruit (Artocarpus heterophyllus). The closely related Artocarpus camansi can be distinguished from A. altilis by having spinier fruits with numerous seeds. Artocarpus mariannensis can be distinguished by having dark green, elongated fruits with darker yellow flesh, as well as entire or shallowly lobed leaves.