Definitions of interloper
(MAINLY ARCHAIC) a person who trades illegally; an unauthorised trader; a traders who operates without paying tax; a person who trespasses on a trade monopoly
The amount of interloper trade off the West African coast is difficult to quantify as they were less likely to keep detailed records than their legal counterparts .
a person who becomes involved with something without being asked, often without any reason to do so
As a hunter, he is an interloper and an exploiter of peaceable nature.
a person who enters a place without permission
My client believed she was still having a relationship with Mr Bunni and saw the unfortunate Ms Boiler as an interloper.