Origin of demesne
- Anglo-French respelling (probably influenced by French mesne) (variant of Anglo-Norman meen middle) (in legal phrase mesne lord lord who holds a manor of a superior lord) of Middle English demeine from Anglo-Norman from Old French demaine domain
From American Heritage Dictionary of the English Language, 5th Edition
- From Anglo-Norman demeyne, demene et al., Old French demeine, demaine, demeigne, domaine (“power”) (whence French domaine (“domain”)), a noun use of an adjective, from Latin dominicus (“belonging to a lord or master”), from dominus (“master, proprietor, owner”). See dame, and compare demain, domain.