interloping

from The Collaborative International Dictionary of English v.0.48

Interlope \In`ter*lope"\, v. i. [imp. & p. p. {Interloped}; p.
   pr. & vb. n. {Interloping}.] [See {Interloper}.]
   To run between parties and intercept without right the
   advantage that one should gain from the other; to traffic
   without a proper license; to intrude; to forestall others; to
   intermeddle.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

25 Moby Thesaurus words for "interloping":
      encroachment, entrance, entrenchment, impingement, imposition,
      incursion, infiltration, influx, infringement, injection, inroad,
      insinuation, interference, interjection, interposition,
      interposure, interruption, intervention, intrusion, invasion,
      irruption, obtrusion, trespass, trespassing, unlawful entry

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