The Collaborative International Dictionary of English v.0.48:

AEsthesis \[AE]s*the""sis\, n. [Gr. ?.]
   Sensuous perception. [R.] --Ruskin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

aesthesis
    n 1: an unelaborated elementary awareness of stimulation; "a
         sensation of touch" [syn: sensation, esthesis,
         aesthesis, sense experience, sense impression, sense
         datum]