Source : Webster's Revised Unabridged Dictionary (1913)

Fail \Fail\v. i. [imp. & p. p. {Failed}; p. pr. & vb. n.
   {Failing}.] [F. failir, fr. L. fallere, falsum, to deceive,
   akin to E. fall. See {Fail}, and cf. {Fallacy}, {False},
   {Fault}.]
   1. To be wanting; to fall short; to be or become deficient in
      any measure or degree up to total absence; to cease to be
      furnished in the usual or expected manner, or to be
      altogether cut off from supply; to be lacking; as, streams
      fail; crops fail.

            As the waters fail from the sea.      --Job xiv. 11.

            Till Lionel's issue fails, his should not reign.
                                                  --Shak.

   2. To be affected with want; to come short; to lack; to be
      deficient or unprovided; -- used with of.

            If ever they fail of beauty, this failure is not be
            attributed to their size.             --Berke.

   3. To fall away; to become diminished; to decline; to decay;
      to sink.

            When earnestly they seek Such proof, conclude they
            then begin to fail.                   --Milton.

   4. To deteriorate in respect to vigor, activity, resources,
      etc.; to become weaker; as, a sick man fails.

   5. To perish; to die; -- used of a person. [Obs.]

            Had the king in his last sickness failed. --Shak.

   6. To be found wanting with respect to an action or a duty to
      be performed, a result to be secured, etc.; to miss; not
      to fulfill expectation.

            Take heed now that ye fail not to do this. --Ezra
                                                  iv. 22.

            Either my eyesight fails, or thou look'st pale.
                                                  --Shak.

   7. To come short of a result or object aimed at or desired;
      to be baffled or frusrated.

            Our envious foe hath failed.          --Milton.

   8. To err in judgment; to be mistaken.

            Which ofttimes may succeed, so as perhaps Shall
            grieve him, if I fail not.            --Milton.

   9. To become unable to meet one's engagements; especially, to
      be unable to pay one's debts or discharge one's business
      obligation; to become bankrupt or insolvent.

Failing \Fail"ing\, n.
   1. A failing short; a becoming deficient; failure;
      deficiency; imperfection; weakness; lapse; fault;
      infirmity; as, a mental failing.

            And ever in her mind she cas about For that
            unnoticed failing in herself.         --Tennyson.

   2. The act of becoming insolvent of bankrupt.

   Syn: See {Fault}.

Source : WordNet®

failing
     adj 1: unable to meet financial obligations; "a failing business
            venture" [syn: {failed}]
     2: below acceptable in performance; "received failing grades"
     n 1: a flaw or weak point; "he was quick to point out his wife's
          failings" [syn: {weakness}]
     2: failure to reach a minimum required performance; "his
        failing the course led to his disqualification" [ant: {passing}]