noun. One who trespasses, or commits a trespass; one who invades another's property or rights, or who does a wrongful act.

noun. One who enters upon another's land, or violates his rights.

noun. A transgressor of the moral law; an offender; a sinner.

noun. One who trespasses; an interloper.

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

"If the trespasser is a child, you face a greater risk of liability, especially if the child was drawn to your property by an “attractive nuisance,” such as a pond or high tower or some fascinating machine."

trespass  trépasser  

entrant  persona non grata  unwelcome person  

alien  boarder  crasher  encroacher  gatecrasher  

above  backslider  blusterer  calumniation  cuddle  

offender  sinner