interloper — English Dictionary

Noun

1. One who interferes, intrudes, or gets involved where not welcome; particularly, a self-interested intruder.

   Examples

   They disliked the interloper, and forced him to leave.

   More examples (1)

   In a button-up plaid shirt with an unwieldly suitcase, he is an interloper from another world – one whose first social faux pas is to make his way slowly through the various gates and arrive at the imposing front door on foot, rather than wait to be picked up from the train station by a servant.

2. An unlicensed or illegitimate trader.

   Usage

   • Obsolete

Noun

1. someone who intrudes on the privacy or property of another without permission

   Synonyms

   intrudertrespasser

   Broader terms

   entrantunwelcome personpersona non grata