Source : Webster's Revised Unabridged Dictionary (1913)

Interfere \In`ter*fere"\, v. i. [imp. & p. p. {Interfered}; p.
   pr. & vb. n. {Interfering}.] [OF. entreferir to strike each
   other; entre between (L. inter) + OF. ferir to strike, F.
   f['e]rir, fr. L. ferire. See {Ferula}.]
   1. To come in collision; to be in opposition; to clash; as,
      interfering claims, or commands.

   2. To enter into, or take a part in, the concerns of others;
      to intermeddle; to interpose.

            To interfere with party disputes.     --Swift.

            There was no room for anyone to interfere with his
            own opinions.                         --Bp.
                                                  Warburton.

   3. To strike one foot against the opposite foot or ankle in
      using the legs; -- sometimes said of a human being, but
      usually of a horse; as, the horse interferes.

   4. (Physics) To act reciprocally, so as to augment, diminish,
      or otherwise affect one another; -- said of waves, rays of
      light, heat, etc. See {Interference}, 2.

   5. (Patent Law) To cover the same ground; to claim the same
      invention.

   Syn: To interpose; intermeddle. See {Interpose}.

Source : WordNet®

interfere
     v 1: come between so as to be hindrance or obstacle; "Your
          talking interferes with my work!"
     2: get involved, so as to alter or hinder an action, or through
        force or threat of force; "Why did the U.S. not intervene
        earlier in WW II?" [syn: {intervene}, {step in}, {interpose}]