soapberry

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various chiefly tropical trees of the genus Sapindus, having pulpy fruit that lathers like soap.
2. n. The fruit of any of these trees.
3. n. The buffalo berry.

Century Dictionary and Cyclopedia

1. n. The fruit of one of several species of Sapindus; also, any of the trees producing it, and, by extension, any member of the genus. The fruit of the proper soapberries so abounds in saponin as to serve the purpose of soap. That of S. Saponaria, a small tree of South America, the West Indies, and Florida, is much used in the West Indies for cleansing linen, etc., and is said to be extremely efficacious, though with frequent use deleterious to the fabric. Its roots also contain saponin. Its hard black seeds are made up into rosaries and necklaces, and sometimes have been used as buttons. In the East Indies the fruit of S. trifoliatus appears to have been used as a detergent from remote times. The pulp is regarded also as astringent, anthelmintic, and tonic, and the seeds yield a medicinal oil. The wood is made into combs and other small articles. This species is sometimes called Indian filbert, translating the Mohammedan name. S. (Dittelasma) Rarak, of Cochin-China, etc., has also a detergent property. The wood of S. acuminatus (S. marginatus), of the southern United States, etc., is hard and strong, easily split into strips, and in the southwest much used for making cotton-baskets and the frames of pack-saddles. Its berries are reddish-brown, of the size of a cherry, with a soapy pulp. Also called wild china-tree (which see, under china-tree). The fruit of some species yields an edible pulp_t though the seed is poisonous. Another name, especially of S. trifoliatus, is soapnut.

Wiktionary

1. n. botany Any woody plant of the genus Sapindus, which is eponymous of the Sapindaceae family
2. n. The fruit of such a plant, especially of the tree Sapindus saponaria.

WordNet 3.0

1. n. a tree of the genus Sapindus whose fruit is rich in saponin