Castellan derives from Medieval Latin castellānus (castle governor), from Latin castellum (fort), and once designated one of the most powerful local officials in feudal Europe.
The governor or warden of a castle, historically responsible for its defense and administration
Castellan entered Middle English from Anglo-Norman French castelain, from Medieval Latin castellānus (governor of a castle), an adjective-turned-noun from Latin castellum (fort, castle), the diminutive of castrum (fortified place, camp). Latin castrum is of uncertain ultimate origin, though some scholars connect it to a PIE root meaning 'to cut' (referring to a ditch or fortification cut from the earth). The castellan held one of the most important offices