bombax, common name for the Bombacaceae, a family of deciduous trees, often tall and with unusually thick trunks, found chiefly in the American tropics. The family includes many commercially important members, e.g., the baobab; the balsa, or corkwood (Ochroma lagopus), which yields the lightest lumber in the world; and the kapok and several species of the genera Bombax and Ceriba whose seed fibers are used as filling material. The Bombacaceae are classified in the division Magnoliophyta, class Magnoliopsida, order Malvales.