The Collaborative International Dictionary of English v.0.48:

Stylish \Styl"ish\, a.
   Having style or artistic quality; given to, or fond of, the
   display of style; highly fashionable; modish; as, a stylish
   dress, house, manner. -- Styl"ish*ly, adv. --
   Styl"ish*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stylishness
    n 1: elegance by virtue of being fashionable [syn: chic,
         chicness, chichi, modishness, smartness,
         stylishness, swank, last word]