Catechu is an extract of any of several species of Acacia—but especially Acacia catechu—produced by boiling the wood in water and evaporating the resulting brew. Catechu is an astringent and has been used since ancient times in ayurvedic medicine as well as in breath-freshening spice mixtures.

Also called cutch, it is a brown dye used for tanning and dyeing and for preserving fishnets and sails.

White cutch, also known as gambier, gambeer, or gambir, has the same uses.