aka "unregistered runner," aka "turkey," aka "bandit," a term used to refer to a runner who "participates" in a race without officially entering the race.
During the 17th century many attempts were made by various merchants or groups of merchants to break into the East India Company's monopoly of trade. These were known at that time as 'interlopers', another term for trespassers.
A grantor on a deed or other document outside the chain of title. A deeds to B who deeds to C. And X deeds to Y. X and Y are interlopers because they are outside of the chain of title.