Guarana (Paullinia cupana) is a climbing plant in the Sapindaceae family, native to the Amazon basin. While guarana features large leaves and clusters of flowers, it is best known for its fruit, which is about the size of a coffee berry.

The guarana fruit's color ranges from orange to red and contains black seeds which are partly covered by white arils. The color contrast when the fruit has been split open has been likened to eyeballs; this has formed the basis of a myth.

The word guarana comes from the Portuguese guaraná, which has its origins in the Sateré-Mawé language word warana.