Source : Webster's Revised Unabridged Dictionary (1913)

AEsthetics \[AE]s*thet"ics\, Esthetics \Es*thet"ics\ (?; 277),
   n. [Gr. ? perceptive, esp. by feeling, fr. ? to perceive,
   feel: cf. G. ["a]sthetik, F. esth['e]tique.]
   The theory or philosophy of taste; the science of the
   beautiful in nature and art; esp. that which treats of the
   expression and embodiment of beauty by art.

Source : WordNet®

aesthetics
     n : (art) the branch of philosophy dealing with beauty and taste
         (emphasizing the evaluative criteria that are applied to
         art); "traditional aesthetics assumed the existence of
         universal and timeless criteria of artistic value" [syn:
         {esthetics}]