1. At common law, land held in one’s own right, and not through a superior; esp., land attached to a manor and reserved for the court’s own use.
2. Domain; realm. — Also spelled demain.
ancient demesne. Hist. A manor that was held by the Crown at the time of William the Conqueror and was recorded in the Domesday Book.
demesne as of fee. Hist. Complete ownership of something.
“But there is this distinction between the two species of hereditaments: that, of a corporeal inheritance a man shall be said to be seised in his demesne, as of fee; of an incorporeal one, he shall only be said to be seised as of fee, and not in his demesne. For, as incorporeal hereditaments are in their nature collateral to, and issue out of, lands and houses, their owner hath no property, dominicum, or demesne, in the thing itself, but hath only something derived out of it; resembling the servitutes, or services, of the civil law.” 2 William Blackstone, Commentaries on the Laws of England 106 (1766).