Ceiba pentandra is a tropical tree of the order Malvales and the family Malvaceae (previously separated in the family Bombacaceae), native to Mexico, Central America and the Caribbean, northern South America, and (as the variety C. pentandra var. guineensis) to tropical west Africa. Kapok is the most used common name for the tree and may also refer to the fibre obtained from its seed pods. The tree is also known as the Java cotton, Java kapok, Silk cotton or ceiba. It is a sacred symbol in Maya mythology.

The tree grows to 60–70 m (200–230 ft) tall and has a very substantial trunk up to 3 m (10 ft) in diameter with buttresses. The trunk and many of the larger branches are often (but not always) crowded with very large, robust simple thorns. The leaves are compound of 5 to 9 leaflets, each up to 20 cm (8 in) and palm like. Adult trees produce several hundred 15 cm (6 in) seed pods. The pods contain seeds surrounded by a fluffy, yellowish fibre that is a mix of lignin and cellulose.

The fibre is light, very buoyant, resilient and resistant to water. The process of harvesting and separating the fibre is labour-intensive and manual. It is difficult to spin but is used as an alternative to down as filling in mattresses, pillows, upholstery, zafus, and stuffed toys such as teddy bears, and for insulation. It was previously much used in life jackets and similar devices until synthetic materials largely replaced the fibre. The seeds produce an oil used locally in soap and that can be used as fertilizer.