burglar (n.)
1540s, shortened from Anglo-Latin burglator (late 13c.), earlier burgator, from Medieval Latin burgator "burglar," from burgare "to break open, commit burglary," from Latin burgus "fortress, castle," a Germanic loan-word akin to borough. The intrusive -l- is perhaps from influence of Latin latro "thief" (see larceny). The native word, Old English burgh-breche, might have influenced the word.