trimethyl-derivative of xanthine, 1830, from German Kaffein, coined by chemist F.F. Runge (1795-1867), apparently from German Kaffee "coffee" (see coffee) + chemical suffix -ine (2) (German -in). So called because the alkaloid was found in coffee beans; its presence accounts for the stimulating effect of coffee and tea. The form of the English word may be via French caféine. Related: Caffeinic.