Catechu

Catechu (/ˈkætᵻʃuː/ or /ˈkætᵻtʃuː/) is an extract of acacia trees used variously as a food additive, astringent, tannin, and dye. It is extracted from several species of Acacia, but especially Senegalia catechu (Acacia catechu), by boiling the wood in water and evaporating the resulting brew. It is also known as cutch, black cutch, cachou, cashoo, khoyer, terra Japonica, or Japan earth, and also katha in Hindi, kaath in Marathi, khoyer in Assamese and Bengali, and kachu in Malay (hence the Latinized Acacia catechu chosen as the Linnaean taxonomy name of the type-species Acacia plant which provides the extract).