The grapefruit (Citrus × paradisi) is a subtropical citrus tree known for its sour to semi-sweet, somewhat bitter fruit. Grapefruit is a hybrid originating in Barbados as an accidental cross between two introduced species, sweet orange (C. sinensis) and pomelo or shaddock (C. maxima), both of which were introduced from Asia in the seventeenth century. When found, it was named the “forbidden fruit”; and frequently, it has been misidentified with the pomelo.

The grapefruit's name alludes to clusters of the fruit on the tree, which often appear similar to that of grapes.