Eng. Law. The name given to that portion of the lands of a manor which the lord retained in his own hands for the use of himself and family. These lands were called terra dominicales or demesne lands, because they were occupied by the lord, or dominus manerii, and his servants, etc.
A man is said to be seised in his demesne as of fee of a corporeal inheritance, because he has a property dominicum or demesne in the thing itself. But when he has no dominion in the thing itself, as in the case of an incorporeal hereditament, he is said to be seised as of fee, and not in his demesne as of fee.
Formerly it was the practice in an action on the case, e.g., for a nuisance to real estate, to aver in the declaration the seisin of the plaintiff in demesne as of fee; and this is still necessary in order to estop the record with the land; so that it may run with or attend the title. But such an action may be maintained on the possession as well as on the seisin, although the effect of the record in this case upon the title would not be the same.