The Collaborative International Dictionary of English v.0.48:

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.]
   [1913 Webster]
   1. To come in collision; to be in opposition; to clash; --
      usually used with with; as, interfering claims, or
      commands; workers in a crowded shop may interfere with
      each other's activity.
      [1913 Webster +PJC]

   2. To enter into, or take a part in, the concerns of others;
      to intermeddle; to interpose; -- used with in or with; as,
      to interfere with the way I raise my children.
      [1913 Webster +PJC]

            To interfere with party disputes.     --Swift.
      [1913 Webster]

            There was no room for anyone to interfere with his
            own opinions.                         --Bp.
                                                  Warburton.
      [1913 Webster]

   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.
      [1913 Webster]

   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.
      [1913 Webster]

   5. (Patent Law) To cover the same ground; to claim the same
      invention; as, to interfere with another patent.
      [1913 Webster]

   Syn: To interpose; intermeddle. See Interpose.
        [1913 Webster]

WordNet (r) 3.0 (2006):

interfering
    adj 1: intrusive in a meddling or offensive manner; "an
           interfering old woman"; "bustling about self-importantly
           making an officious nuisance of himself"; "busy about
           other people's business" [syn: interfering,
           meddlesome, meddling, officious, busy,
           busybodied]