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]

WordNet (r) 3.0 (2006):

interlope
    v 1: encroach on the rights of others, as in trading without a
         proper license

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "interlope":
   barge in, break in, break in upon, burst in, butt in, charge in,
   come between, crash, crash in, crash the gates, creep in, crowd in,
   cut in, edge in, elbow in, encroach, entrench, foist in, horn in,
   impinge, impose, impose on, impose upon, infiltrate, infringe,
   insinuate, interfere, interpose, intervene, intrude, invade,
   irrupt, obtrude, press in, push in, put on, put upon, rush in,
   smash in, sneak in, squeeze in, steal in, storm in, throng in,
   thrust in, trench, trespass, work in, worm in