What is the legal term for an unauthorized use of another person's property?

The correct legal term for an unauthorized use of another person's property is trespass. This term specifically refers to the act of entering someone's land or property without permission, thereby infringing on the rights of the property owner. Trespass can occur whether or not the trespasser intends to cause harm; the mere act of entering without consent constitutes trespass.

In this context, understanding trespass is crucial, as it highlights the importance of property rights and the requirement for consent in the use of someone else's property. It differentiates from other terms, such as adverse possession, which specifically involves long-term unauthorized usage that can lead to legal claims of ownership over a period. Encroachment relates to situations where a property owner’s structure or way extends onto a neighbor's property, but it is not inherently about unauthorized use. Illegal use is a broader term that lacks the precise legal definition and implications associated with property law compared to trespass.