Interlope :: Interlope (v. i.) 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.
Interloper :: Interloper (n.) One who interlopes; one who interlopes; one who unlawfully intrudes upon a property, a station, or an office; one who interferes wrongfully or officiously..