n. A name common to several astringent extracts prepared from the wood, bark, and fruit of various plants.n. It is used extensively in cotton-dyeing, under the name of cutch, for the production of tan shades. It consists chiefly of two principles, catechu-tannic acid, and catechin or catechuic acid, which are accompanied by a brown amorphous substance called japonic acid. Japonic acid is the final oxidation-product of catechuic acid, and catechu-tannic acid is an intermediate oxidation-product. Bombay catechu, obtained from the heart-wood of the catechu palm. Areca Catechu, is considered the best quality for dyeing purposes; its principal constituent is catechu-tannic acid. Bengal catechu, obtained from the pods and twigs of the acacia, is less soluble than Bombay catechu. Cube catechu is the same as gambier catechu, which is a product of the leaves of Ouronparia Gambier and is sold in the form of yellow cubes.