The Collaborative International Dictionary of English v.0.48:

Exhibitioner \Ex`hi*bi"tion*er\, n. (Eng. Univ.)
   One who has a pension or allowance granted for support.
   [1913 Webster]

         A youth who had as an exhibitioner from Christ's
         Hospital.                                --G. Eliot.
   [1913 Webster]

WordNet (r) 3.0 (2006):

exhibitioner
    n 1: someone who organizes an exhibit for others to see [syn:
         exhibitor, exhibitioner, shower]