citrus vs mandarin orange

citrus

noun
  • Any of several shrubs or trees of the genus Citrus in the family Rutaceae. 

  • The fruit of such plants, generally spherical, oblate, or prolate, consisting of an outer glandular skin (called zest), an inner white skin (called pith or albedo), and generally between 8 and 16 sectors filled with pulp consisting of cells with one end attached to the inner skin. Citrus fruits include orange, grapefruit, lemon, lime, and citron. 

adj
  • Of, relating to, or similar to citrus plants or fruit. 

mandarin orange

noun
  • A small citrus tree (Citrus reticulata) with fruit resembling the orange. 

  • The fruit of this tree, smaller than an orange and oblate. In daily usage, it may include other similar citrus fruits like Citrus unshiu (satsuma or mikan) Citrus tangerina (tangerine). 

How often have the words citrus and mandarin orange occurred in a corpus of books? (source: Google Ngram Viewer )