moat
UK: məʊt | US: moʊt
n. a deep, wide ditch surrounding a castle, fort, or town, typically filled with water and intended as a defense against attack.
The word "moat" originates from Old French "mote" (meaning "mound, hillock, or embankment"), which later evolved to refer specifically to a defensive ditch. It entered Middle English as "mote" and eventually became "moat" by the 14th century. The shift in meaning reflects the transition from earthen mounds to water-filled trenches as primary fortification structures in medieval Europe.
The castle was protected by a deep moat filled with water.
Archaeologists discovered remnants of an ancient moat around the ruined fortress.
The king ordered the moat to be dug wider to deter invaders.
Swans glided gracefully across the castle's moat.
Modern security systems have replaced the need for physical moats in architecture.