The word 'walled' is a straightforward English formation from the noun 'wall'. The root 'wall' entered Old English from Latin 'vallum', which referred to a palisade or rampart, a meaning that has persisted in its core sense of a solid vertical structure for enclosure or defense. The adjectival suffix '-ed', of Germanic origin, is a highly productive element in English for creating descriptive terms meaning 'possessing' or 'provided with'. Therefore, the literal construction 'walled' logically means 'provided with walls', an efficient derivation that perfectly captures its modern meanings of being enclosed, fortified, or defined by such structures.

Structure: wall (noun) + ed (adjective suffix) - wall: From Old English 'weall', meaning a rampart or defensive structure, of Latin origin ('vallum' meaning palisade or rampart). Functions as the core noun root. - ed: A suffix of Old English origin, used to form adjectives from nouns, meaning 'having' or 'characterized by'.