Source : Webster's Revised Unabridged Dictionary (1913)

Yerk \Yerk\, v. t. [imp. & p. p. {Yerked}; p. pr. & vb. n.
   {Yerking}.] [See {Yerk}.]
   1. To throw or thrust with a sudden, smart movement; to kick
      or strike suddenly; to jerk.

            Their wounded steeds . . . Yerk out their armed
            heels at their dead masters.          --Shak.

   2. To strike or lash with a whip. [Obs. or Scot.]