The Collaborative International Dictionary of English v.0.48:

Dulcinea \Dul*cin"e*a\, n. [Sp., from Dulcinea del Toboso the
   mistress of the affections of Don Quixote.]
   A mistress; a sweetheart.
   [1913 Webster]

         I must ever have some Dulcinea in my head. --Sterne.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dulcinea
    n 1: a woman who is a man's sweetheart [syn: ladylove,
         dulcinea]