What describes a situation where an object crosses onto another's property boundary?

The term that best describes a situation where an object crosses onto another person's property boundary is encroachment. This occurs when a structure, tree, or any part of a property extends over the property line into neighboring land. Encroachments can lead to disputes between property owners, as it infringes upon the rights and ownership boundaries legally established.

In contrast, an easement involves the legal right to use a portion of someone else's property for a specific purpose, such as a utility line or path. This right does not mean that the property is being encroached upon; rather, it's an agreement that has been legally documented.

Adverse possession refers to a legal doctrine that allows a person to claim ownership of land under certain conditions, typically after occupying it for a specified period without the consent of the true owner. This is distinct from the idea of an object simply crossing a boundary.

Property infringement is a general term that can denote any violation of property rights but is not specifically used to describe the physical crossing of property boundaries by an object. Therefore, encroachment is the most accurate term to describe this situation.