Source : Webster's Revised Unabridged Dictionary (1913)

Lose \Lose\, v. t. [imp. & p. p. {Losing}.] [OE. losien to
   loose, be lost, lose, AS. losian to become loose; akin to OE.
   leosen to lose, p. p. loren, lorn, AS. le['o]san, p. p. loren
   (in comp.), D. verliezen, G. verlieren, Dan. forlise, Sw.
   f["o]rlisa, f["o]rlora, Goth. fraliusan, also to E. loose, a
   & v., L. luere to loose, Gr. ?, Skr. l? to cut. [root]127.
   Cf. {Analysis}, {Palsy}, {Solve}, {Forlorn}, {Leasing},
   {Loose}, {Loss}.]
   1. To part with unintentionally or unwillingly, as by
      accident, misfortune, negligence, penalty, forfeit, etc.;
      to be deprived of; as, to lose money from one's purse or
      pocket, or in business or gaming; to lose an arm or a leg
      by amputation; to lose men in battle.

            Fair Venus wept the sad disaster Of having lost her
            favorite dove.                        --Prior.

   2. To cease to have; to possess no longer; to suffer
      diminution of; as, to lose one's relish for anything; to
      lose one's health.

            If the salt hath lost his savor, wherewith shall it
            be salted ?                           --Matt. v. 13.

   3. Not to employ; to employ ineffectually; to throw away; to
      waste; to squander; as, to lose a day; to lose the
      benefits of instruction.

            The unhappy have but hours, and these they lose.
                                                  --Dryden.

   4. To wander from; to miss, so as not to be able to and; to
      go astray from; as, to lose one's way.

            He hath lost his fellows.             --Shak

   5. To ruin; to destroy; as destroy; as, the ship was lost on
      the ledge.

            The woman that deliberates is lost.   --Addison.

   6. To be deprived of the view of; to cease to see or know the
      whereabouts of; as, he lost his companion in the crowd.

            Like following life thro' creatures you dissect, You
            lose it in the moment you detect.     --Pope.

   7. To fail to obtain or enjoy; to fail to gain or win; hence,
      to fail to catch with the mind or senses; to miss; as, I
      lost a part of what he said.

            He shall in no wise lose his reward.  --Matt. x. 42.

            I fought the battle bravely which I lost, And lost
            it but to Macedonians.                --Dryden.

   8. To cause to part with; to deprive of. [R.]

            How should you go about to lose him a wife he loves
            with so much passion ?                --Sir W.
                                                  Temple.

   9. To prevent from gaining or obtaining.

            O false heart ! thou hadst almost betrayed me to
            eternal flames, and lost me this glory. --Baxter.

   {To lose ground}, to fall behind; to suffer gradual loss or
      disadvantage.

   {To lose heart}, to lose courage; to become timid. ``The
      mutineers lost heart.'' --Macaulay.

   {To lose one's head}, to be thrown off one's balance; to lose
      the use of one's good sense or judgment.

            In the excitement of such a discovery, many scholars
            lost their heads.                     --Whitney.

   {To lose one's self}.
      (a) To forget or mistake the bearing of surrounding
          objects; as, to lose one's self in a great city.
      (b) To have the perceptive and rational power temporarily
          suspended; as, we lose ourselves in sleep.

   {To lose sight of}.
      (a) To cease to see; as, to lose sight of the land.
      (b) To overlook; to forget; to fail to perceive; as, he
          lost sight of the issue.

Losing \Lo"sing\, a. [See {Losenger}.]
   Given to flattery or deceit; flattering; cozening. [Obs.]

         Amongst the many simoniacal that swarmed in the land,
         Herbert, Bishop of Thetford, must not be forgotten;
         nick-named Losing, that is, the Fratterer. --Fuller.

Losing \Los"ing\, a. [See {Lose}, v. t.]
   Causing or incurring loss; as, a losing game or business.

         Who strive sit out losing hands are lost. --Herbert.

Source : Free On-Line Dictionary of Computing

losing
     
         Said of anything that is or causes a {lose} or
        {lossage}.
     
        [{Jargon File}]