The Collaborative International Dictionary of English v.0.48:

Favoritism \Fa"vor*it*ism\, n. [Cf. F. favoritisme.]
   The disposition to favor and promote the interest of one
   person or family, or of one class of men, to the neglect of
   others having equal claims; partiality.
   [1913 Webster]

         A spirit of favoritism to the Bank of the United
         States.                                  --A. Hamilton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

favoritism
    n 1: an inclination to favor some person or group [syn:
         favoritism, favouritism]
    2: unfair treatment of a person or group on the basis of
       prejudice [syn: discrimination, favoritism,
       favouritism]