a hard, brown substance obtained from an Asiatic acacia (Acacia catechu) and other Asiatic trees and shrubs: used as an astringent in medicine, and for dyeing, tanning, etc.
See catechu in American Heritage Dictionary 4
(kătˈə-cho͞oˌ)
noun
a. A spiny Asian tree (Acacia catechu) having bipinnately compound leaves, spikes of yellow flowers, and dark heartwood.
b. A raw material obtained from the heartwood of this plant, used in the preparation of tannins and brown dyes. Also called cutch.