The degree, quantity, or nature of a person’s interest in real property is called his

Dower is an outdated common law right that gave a widow a life estate in one-third of her deceased husband's real property. It doesn't refer to the general nature of property interests but is a specific, limited right that has been abolished or modified in most states.

Curtesy was a common law right that gave a widower a life estate in his deceased wife's real property if they had borne a child together. Like dower, it's a specific historical right, not the general term for property interests.

Possession refers only to the physical control or occupation of property, which is just one aspect of an estate. An estate encompasses both possession and the legal rights that come with ownership, making it a broader concept.