What principal characteristic defines a servient estate?

The principal characteristic that defines a servient estate is that it bears the burden of a servitude. In property law, a servient estate is typically the property that is subject to an easement or servitude, allowing another party (the dominant estate) certain rights over it. For example, if one property owner has the right to cross another's land to access their own property, the land that is being crossed is the servient estate, which is obligated to allow that access.

Understanding this concept is crucial when dealing with real property interests and the rights associated with easements. The servient estate's obligation to accommodate the uses granted to the dominant estate is what makes it distinct.

The other options do not accurately describe the defining characteristics of a servient estate. They may touch on related concepts but do not capture the essence of what establishes a servient estate's role in relation to a dominant estate.