Guaranine \Gua"ra*nine`\, n. (Chem.) An alkaloid extracted from guarana. Same as {Caffeine}. [1913 Webster]
caffein \caf*fe"in\, Caffeine \Caf*fe"ine\, n. [Cf. F. caf['e]ine. See {Coffee}.] (Chem.) A white, bitter, crystallizable substance, found in coffee and tea. It is identical with the alkaloid {theine} from tea leaves, and with {guaranine} from guarana. It is responsible for most of the stimulating effect of coffee or tea. [1913 Webster + WordNet 1.5]