any semiparasitic plant of the genus Santalum (family Santalaceae), especially the fragrant wood of the true, or white, sandalwood, Santalum album. The approximately 10 species of Santalum are distributed throughout southeastern Asia and the islands of the South Pacific.

Many other woods are used as substitutes for true sandalwood. Red sandalwood is obtained from the reddish-coloured wood of Pterocarpus santalinus, a Southeast Asian tree of the pea family (Fabaceae). This species may have been the source of the sandalwood used in King Solomon's temple.

A true sandalwood tree grows to a height of about 10 metres (33 feet); has leathery leaves in pairs, each opposite the other on the branch; and is partially parasitic on the roots of other tree species. Both tree and roots contain a yellow aromatic oil, called sandalwood oil, the odour of which persists for years in such articles as ornamental boxes, furniture, and fans made of the white sapwood. The oil is obtained by steam distillation of the wood and is used in perfumes, soaps, candles, incense, and folk medicines. Powdered sandalwood is used in the paste applied to make Brahman caste marks and in sachets for scenting clothes.

Sandalwood trees have been cultivated since antiquity for their yellowish heartwood, which plays a major role in many Oriental funeral ceremonies and religious rites. The trees are slow growing, usually taking about 30 years for the heartwood to reach an economically useful thickness.