The Collaborative International Dictionary of English v.0.48:

Traction \Trac"tion\, n. [L. trahere, tractum, to draw: cf. F.
   traction.]
   1. The act of drawing, or the state of being drawn; as, the
      traction of a muscle.
      [1913 Webster]

   2. Specifically, the act of drawing a body along a plane by
      motive power, as the drawing of a carriage by men or
      horses, the towing of a boat by a tug.
      [1913 Webster]

   3. Attraction; a drawing toward. [R.]
      [1913 Webster]

   4. The adhesive friction of a wheel on a rail, a rope on a
      pulley, or the like; as, the car is stuck in the snow
      because it can;t get any traction. --Knight.
      [1913 Webster +PJC]

   Angle of traction (Mech.), the angle made with a given
      plane by the line of direction in which a tractive force
      acts.

   Traction engine, a locomotive for drawing vehicles on
      highways or in the fields.
      [1913 Webster]

WordNet (r) 3.0 (2006):

traction
    n 1: the friction between a body and the surface on which it
         moves (as between an automobile tire and the road) [syn:
         grip, traction, adhesive friction]
    2: (orthopedics) the act of pulling on a bone or limb (as in a
       fracture) to relieve pressure or align parts in a special way
       during healing; "his leg was in traction for several days"