Encroachment refers to the unlawful intrusion or extension of one property owner's land or structure onto another's property. encroachment - Meaning in Law and Legal Documents, Examples and FAQs Encroachment, or invasion, happens when someone builds or uses part of their property that crosses over into someone else's land. An encroachment is something that intrudes and has the power to influence whatever it encounters. Some might consider text messaging to be an encroachment of impersonal technology on true, heartfelt interactions. Encroachment carries the sense of something slowly creeping into something else's space, either literally or figuratively. encroachment noun intrusion, invasion, violation, infringement, trespass, incursion, usurpation, inroad, impingement This is a sign of the encroachment of commercialism in medicine.