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.