Pronunciation: (si'trus),[key] —n., —pl.-rus•es. 1. any small tree or spiny shrub of the genus Citrus, of the rue family, including the lemon, lime, orange, tangerine, grapefruit, citron, kumquat, and shaddock, widely cultivated for fruit or grown as an ornamental.
2. the tart-to-sweet, pulpy fruit of any of these trees or shrubs, having a characteristically smooth, shiny, stippled skin.
—adj. Also,cit'rous.of or pertaining to such trees or shrubs, or their fruit.