Source : Webster's Revised Unabridged Dictionary (1913)

Tractor \Tract"or\, n.
   An a["e]roplane flying machine having one or more tractor
   screws.

Tractor \Tract"or\, n. [NL., from L. trahere, tractum, to draw.]
   1. That which draws, or is used for drawing.

   2. pl. (Med.) Two small, pointed rods of metal, formerly used
      in the treatment called Perkinism.

Source : WordNet®

tractor
     n 1: a wheeled vehicle with large wheels; used in farming and
          other applications
     2: a truck that has a cab but no body; used for pulling large
        trailers or vans