kumquat

noun

1. a small, round or oblong citrus fruit having a sweet rind and acid pulp, used chiefly for preserves.
2. any of several citrus shrubs of the genus Fortunella, native to China, that bear this fruit.

noun

1. any of several small Chinese trees of the rutaceous genus Fortunella
2. the small round orange fruit of such a tree, with a sweet rind, used in preserves and confections