trespasser n: one who trespasses
: one who enters or remains on the real property of another wrongfully or without the owner's or possessor's authority or consent compare invitee , licensee NOTE: The general rule is that the owner or possessor of real property has the duty merely to refrain from willfully, wantonly, or recklessly injuring a trespasser whose presence is known. This rule is usually applied to licensees as well, although a licensee is usually owed a higher degree of care when an entrance fee is charged or when active operations (as of machinery) are taking place on the property.
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.