guarana Syllabification: (gua·ra·na)Pronunciation: /gwəˈränə/Definition of guarana noun 1a substance prepared from the seeds of a Brazilian shrub, used as a tonic or stimulant. 2the shrub (Paullinia cupana) of the soapberry family that yields guarana. Origin: mid 19th century: from Tupiguarana in other Oxford dictionaries Definition of guarana in the British & World English dictionary