The Collaborative International Dictionary of English v.0.48:

Fail \Fail\, n. [OF. faille, from failir. See Fail, v. i.]
   1. Miscarriage; failure; deficiency; fault; -- mostly
      superseded by failure or failing, except in the phrase
      without fail. "His highness' fail of issue." --Shak.
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   2. Death; decease. [Obs.] --Shak.
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The Collaborative International Dictionary of English v.0.48:

Fail \Fail\, v. t.
   1. To be wanting to; to be insufficient for; to disappoint;
      to desert.
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            There shall not fail thee a man on the throne. --1
                                                  Kings ii. 4.
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   2. To miss of attaining; to lose. [R.]
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            Though that seat of earthly bliss be failed.
                                                  --Milton.
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The Collaborative International Dictionary of English v.0.48:

Fail \Fail\ (f[=a]l) v. i. [imp. & p. p. Failed (f[=a]ld); 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.
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            As the waters fail from the sea.      --Job xiv. 11.
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            Till Lionel's issue fails, his should not reign.
                                                  --Shak.
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   2. To be affected with want; to come short; to lack; to be
      deficient or unprovided; -- used with of.
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            If ever they fail of beauty, this failure is not be
            attributed to their size.             --Berke.
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   3. To fall away; to become diminished; to decline; to decay;
      to sink.
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            When earnestly they seek
            Such proof, conclude they then begin to fail.
                                                  --Milton.
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   4. To deteriorate in respect to vigor, activity, resources,
      etc.; to become weaker; as, a sick man fails.
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   5. To perish; to die; -- used of a person. [Obs.]
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            Had the king in his last sickness failed. --Shak.
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   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.
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            Take heed now that ye fail not to do this. --Ezra
                                                  iv. 22.
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            Either my eyesight fails, or thou look'st pale.
                                                  --Shak.
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   7. To come short of a result or object aimed at or desired;
      to be baffled or frusrated.
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            Our envious foe hath failed.          --Milton.
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   8. To err in judgment; to be mistaken.
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            Which ofttimes may succeed, so as perhaps
            Shall grieve him, if I fail not.      --Milton.
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   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; as, many
      credit unions failed in the late 1980's.
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WordNet (r) 3.0 (2006):

fail
    v 1: fail to do something; leave something undone; "She failed
         to notice that her child was no longer in his crib"; "The
         secretary failed to call the customer and the company lost
         the account" [syn: fail, neglect]
    2: be unsuccessful; "Where do today's public schools fail?";
       "The attempt to rescue the hostages failed miserably" [syn:
       fail, go wrong, miscarry] [ant: bring home the bacon,
       come through, deliver the goods, succeed, win]
    3: disappoint, prove undependable to; abandon, forsake; "His
       sense of smell failed him this time"; "His strength finally
       failed him"; "His children failed him in the crisis" [syn:
       fail, betray]
    4: stop operating or functioning; "The engine finally went";
       "The car died on the road"; "The bus we travelled in broke
       down on the way to town"; "The coffee maker broke"; "The
       engine failed on the way to town"; "her eyesight went after
       the accident" [syn: fail, go bad, give way, die,
       give out, conk out, go, break, break down]
    5: be unable; "I fail to understand your motives" [ant: bring
       off, carry off, manage, negociate, pull off]
    6: judge unacceptable; "The teacher failed six students" [ant:
       pass]
    7: fail to get a passing grade; "She studied hard but failed
       nevertheless"; "Did I fail the test?" [syn: fail, flunk,
       bomb, flush it] [ant: make it, pass]
    8: fall short in what is expected; "She failed in her
       obligations as a good daughter-in-law"; "We must not fail his
       obligation to the victims of the Holocaust"
    9: become bankrupt or insolvent; fail financially and close;
       "The toy company went bankrupt after the competition hired
       cheap Mexican labor"; "A number of banks failed that year"
    10: prove insufficient; "The water supply for the town failed
        after a long drought" [syn: fail, run out, give out]
    11: get worse; "Her health is declining"