Source : Webster's Revised Unabridged Dictionary (1913)

Incompetent \In*com"pe*tent\, a. [L. incompetens: cf. F.
   incomp['e]tent. See {In-} not, and {Competent}.]
   1. Not competent; wanting in adequate strength, power,
      capacity, means, qualifications, or the like; incapable;
      unable; inadequate; unfit.

            Incompetent to perform the duties of the place.
                                                  --Macaulay.

   2. (Law) Wanting the legal or constitutional qualifications;
      inadmissible; as, a person professedly wanting in
      religious belief is an incompetent witness in a court of
      law or equity; incompetent evidence.

            Richard III. had a resolution, out of hatred to his
            brethren, to disable their issues, upon false and
            incompetent pretexts, the one of attainder, the
            other of illegitimation.              --Bacon.

   3. Not lying within one's competency, capacity, or authorized
      power; not permissible.

   Syn: Incapable; unable; inadequate; insufficient;
        inefficient; disqualified; unfit; improper.

   Usage: {Incompetent}, {Incapable}. Incompetent is a relative
          term, denoting a want of the requisite qualifications
          for performing a given act, service, etc.; incapable
          is absolute in its meaning, denoting want of power,
          either natural or moral. We speak of a man as
          incompetent to a certain task, of an incompetent
          judge, etc. We say of an idiot that he is incapable of
          learning to read; and of a man distinguished for his
          honor, that he is incapable of a mean action.

Source : WordNet®

incompetent
     n : someone who is not competent to take effective action [syn:
         {incompetent person}]

incompetent
     adj 1: not qualified or suited for a purpose; "an incompetent
            secret service"; "the filming was hopeless
            incompetent" [ant: {competent}]
     2: showing lack of skill or aptitude; "a bungling workman";
        "did a clumsy job"; "his fumbling attempt to put up a
        shelf" [syn: {bungling}, {clumsy}, {fumbling}]
     3: not doing a good job; "incompetent at chess" [syn: {unskilled}]
     4: not meeting requirements; "unequal to the demands put upon
        him" [syn: {incapable}, {unequal to(p)}]