Final answer:
The term for an object once considered personal property but now attached to land making it part of real property is a Fixture.
Step-by-step explanation:
The term that refers to an object which was once personal property but has since become so attached to land or structures that it is considered legally a part of the real property is known as a Fixture. A fixture is a legal concept that means that something that was once movable or considered personal property has been affixed to property in such a way that it is now legally considered to be part of the real estate. Examples of fixtures include a home's heating system, built-in cabinets, or a fence around property.