Citrus

n.
  1. (Bot.) A genus of trees including the orange, lemon, lime, tangerine, citron, grapefruit, etc., originally natives of southern Asia.
  2. (Bot.) any tree belonging to the genus Citrus, having leathery evergreen leaves and bearing a soft pulpy fruit covered by a thick skin; -- called also citrus tree.
  3. (Bot.) the fruit of a tree belonging to the genus Citrus, having a thick shiny skin and a soft, sweet to tart pulp.