Source : Webster's Revised Unabridged Dictionary (1913)

Sprag \Sprag\, v. t. [imp. & p. p. {Spragged}; p. pr. & vb. n.
   {Spragging}.]
   1. To check the motion of, as a carriage on a steep grade, by
      putting a sprag between the spokes of the wheel. --R. S.
      Poole.

   2. To prop or sustain with a sprag.