caoutchouc (kouˈchŏk) [key], natural rubber obtained as a latex from various tropical plants, e.g., the Pará rubber tree. It is much more elastic than balata or gutta-percha. It is the most familiar and widely used of the natural rubbers. It is usually processed by coagulating the latex and by milling or smoking the solid rubber. It is then further treated, e.g., by vulcanization, to produce useful articles.