in‧ter‧lop‧er /ˈɪntələʊpə $ -tərloʊpər/ 
 noun [countable][
Date: 1500-1600; 
Origin: inter- + -loper (perhaps from Old English hleapan 'to jump' or Middle Dutch lopen 'to run')]
 someone who enters a place or group where they should not be 
 [TahlilGaran] Dictionary of Contemporary English ▲