sour orange
Also Known As:
Bitter orange, Seville orange
What it is:
Fruit
Fruit from the citrus tree, Citrus aurantium. Many varieties of bitter oranges are used for their essential oil, which is used in perfume and as a flavoring. Bitter orange is also used in herbal medicine as a stimulant and appetite suppressant.
Further reading:
http://en.wikipedia.org/wiki/Bitter_orange