An orange—specifically, the sweet orange—is the citrus Citrus ×sinensis (syn. Citrus aurantium L.var. dulcis L., or Citrus aurantium Risso) and its fruit. The orange is a hybrid of ancient cultivated origin, possibly between pomelo (Citrus maxima) and tangerine (Citrus reticulata). It is a small floweringtree growing to about 10 m tall with evergreenleaves, which are arranged alternately, of ovate shape with crenulate margins and 4–10 cm long. The orange fruit is a hesperidium, a type of berry.

Oranges originated in Southeast Asia. The fruit of Citrus sinensis is called sweet orange to distinguish it from Citrus aurantium, the bitter orange. The name is thought to ultimately derive from the Dravidian and Tamil word for the orange tree, with its final form developing after passing through numerous intermediate languages.