The Collaborative International Dictionary of English v.0.48:

aerialist \aer"i*al*ist\ n.
   1. an athlete who performs acts high above the ground on a
      trapeze or high wire, requiring skill and agility and
      coordination.

   Syn: trapeze artist
        [WordNet 1.5 +PJC]

   2. a burglar who gains entrance to buildings from the
      rooftop, sometimes leaping from building to building in
      the process. A type of second-story man. [Slang]
      [PJC]

WordNet (r) 3.0 (2006):

aerialist
    n 1: an acrobat who performs in the air (as on a rope or
         trapeze)