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