Duke of Nemours was a title in the Peerage of France. The name refers to Nemours in the Île-de-France region of north-central France.

The crown lands, crown estate, royal domain or domaine royal of France were the lands, fiefs and rights directly possessed by the kings of France. While the term eventually came to refer to a territorial unit, the royal domain originally referred to the network of "castles, villages and estates, forests, towns, religious houses and bishoprics, and the rights of justice, tolls and taxes" effectively held by the king or under his domination. In terms of territory, before the reign of Henry IV, the domaine royal did not encompass the entirety of the territory of the kingdom of France and for much of the Middle Ages significant portions of the kingdom were the direct possessions of other feudal lords.