2006 New York Code - Trailer.

 
    § 156. Trailer.    Any vehicle not propelled by its own power drawn on
  the public highways by a motor vehicle as defined in section one hundred
  twenty-five operated thereon,  except  motorcycle  side  cars,  vehicles
  being  towed  by a non-rigid support and vehicles designed and primarily
  used for other purposes and only occasionally  drawn  by  such  a  motor
  vehicle.