The Collaborative International Dictionary of English v.0.48:

Fop \Fop\, n. [OE. foppe, fop, fool; cf. E. fob to cheat, G.
   foppen to make a fool of one, jeer, D. foppen.]
   One whose ambition it is to gain admiration by showy dress; a
   coxcomb; an inferior dandy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fop
    n 1: a man who is much concerned with his dress and appearance
         [syn: dandy, dude, fop, gallant, sheik, beau,
         swell, fashion plate, clotheshorse]