Source : Webster's Revised Unabridged Dictionary (1913)

Harness \Har"ness\, v. t. [imp. & p. p. {Harnessed}; p. pr. &
   vb. n. {Harnessing}.] [OE. harneisen; cf. F. harnacher, OF.
   harneschier.]
   1. To dress in armor; to equip with armor for war, as a
      horseman; to array.

            Harnessed in rugged steel.            --Rowe.

            A gay dagger, Harnessed well and sharp as point of
            spear.                                --Chaucer.

   2. Fig.: To equip or furnish for defense. --Dr. H. More.

   3. To make ready for draught; to equip with harness, as a
      horse. Also used figuratively.

            Harnessed to some regular profession. --J. C.
                                                  Shairp.

   {Harnessed antelope}. (Zo["o]l.) See {Guib}.

   {Harnessed moth} (Zo["o]l.), an American bombycid moth
      ({Arctia phalerata} of Harris), having, on the fore wings,
      stripes and bands of buff on a black ground.

Harness \Har"ness\, n. [OE. harneis, harnes, OF. harneis, F.
   harnais, harnois; of Celtic origin; cf. Armor. harnez old
   iron, armor, W. haiarn iron, Armor. houarn, Ir. iarann, Gael.
   iarunn. Gf. {Iron}.]
   1. Originally, the complete dress, especially in a military
      sense, of a man or a horse; hence, in general, armor.

            At least we 'll die witch harness on our back.
                                                  --Shak.

   2. The equipment of a draught or carriage horse, for drawing
      a wagon, coach, chaise, etc.; gear; tackling.

   3. The part of a loom comprising the heddles, with their
      means of support and motion, by which the threads of the
      warp are alternately raised and depressed for the passage
      of the shuttle.

   {To die in harness}, to die with armor on; hence,
      colloquially, to die while actively engaged in work or
      duty.

Source : WordNet®

harness
     n 1: a support consisting of an arrangement of straps for holding
          something to the body (especially one supporting a
          person suspended from a parachute)
     2: stable gear consisting of an arrangement of leather straps
        fitted to a draft animal so that it can be attached to and
        pull a cart

harness
     v 1: put a harness; "harness the horse" [syn: {tackle}] [ant: {unharness}]
     2: exploit the power of; "harness natural forces and resources"
     3: control and direct with or as if by reins; "rein a horse"
        [syn: {rein in}, {draw rein}, {rein}]
     4: keep in check; "rule one's temper" [syn: {rule}, {rein}]