citrus(n = noun.plant) citrus tree - any of numerous tropical usually thorny evergreen trees of the genus Citrus having leathery evergreen leaves and widely cultivated for their juicy edible fruits having leathery aromatic rinds;
A genus of trees including the orange, lemon, lime, tangerine, citron, grapefruit, etc., originally natives of southern Asia. [1913 Webster]
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. [PJC]
the fruit of a tree belonging to the genus Citrus, having a thick shiny skin and a soft, sweet to tart pulp. [PJC]