Source : Webster's Revised Unabridged Dictionary (1913)

Tug \Tug\, n.
   1. A pull with the utmost effort, as in the athletic contest
      called tug of war; a supreme effort.

            At the tug he falls, Vast ruins come along, rent
            from the smoking walls.               --Dryden.

   2. A sort of vehicle, used for conveying timber and heavy
      articles. [Prov. Eng.] --Halliwell.

   3. (Naut.) A small, powerful steamboat used to tow vessels;
      -- called also {steam tug}, {tugboat}, and {towboat}.

   4. A trace, or drawing strap, of a harness.

   5. (Mining.) An iron hook of a hoisting tub, to which a
      tackle is affixed.

   {Tug iron}, an iron hook or button to which a tug or trace
      may be attached, as on the shaft of a wagon.