Seisin

Seisin (or seizin) denotes the legal possession of a feudal fiefdom or fee, that is to say an estate in land. It was used in the form of "the son and heir of X has obtained seisin of his inheritance", and thus is effectively a term concerned with conveyancing in the feudal era. The person holding such estate is said to be "seized of it", a phrase which commonly appears in inquisitions post mortem (i.e. "The jurors find that X died seized of the manor of ..."). The monarch alone "owned" all the land of England by his allodial right and all his subjects were merely his tenants under various contracts of feudal tenure.