Source : Webster's Revised Unabridged Dictionary (1913)

Sprag \Sprag\, n. [Cf. Icel. spraka a small flounder.]
   (Zo["o]l.)
   A young salmon. [Prov. Eng.]

Sprag \Sprag\, n. [See {Spray} a branch.]
   A billet of wood; a piece of timber used as a prop.

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.

Sprag \Sprag\, a.
   See {Sprack}, a. --Shak.

Source : WordNet®

sprag
     n 1: a chock or bar wedged under a wheel or between the spokes to
          prevent a vehicle from rolling down an incline
     2: a wooden prop used to support the roof of a mine [syn: {pitprop}]