Source : Webster's Revised Unabridged Dictionary (1913)

Thurl \Thurl\, n. [AS. [thorn]yrel a hole. [root]53. See
   {Thirl}, {Thrill}.]
   1. A hole; an aperture. [Obs.]

   2. (Mining)
      (a) A short communication between adits in a mine.
      (b) A long adit in a coalpit.

Thurl \Thurl\, v. t. [See {Thrill}.]
   1. To cut through; to pierce. [Obs.] --Piers Plowman.

   2. (Mining) To cut through, as a partition between one
      working and another.