The word is a modern English compound adjective formed by combining two native English roots with a productive suffix. The first element, "thin," originates from the Proto-Germanic thunnuz, which carries the core sense of lack of thickness or density. The second element, "wall," descends from the Latin vallum (a palisade or rampart) via Proto-Germanic, entering Old English with the meaning of a defensive structure. The suffix "-ed" is an ancient adjectival formative. The literal logic of the compound is transparent: "having walls that are thin." It is typically used in technical or descriptive contexts, such as engineering or biology, to describe objects like pipes, cells, or structures where the relative thinness of their boundaries is a defining characteristic.

Structure: thin (adjective) + wall (noun) + ed (adjective-forming suffix) - thin: From Old English þynne, meaning "not thick, slender, sparse." It functions as the core descriptive adjective in the compound. - wall: From Old English weall, meaning "rampart, dike, or structure for defense or enclosure." It functions as the noun specifying the object being described. - ed: A suffix from Old English -ede, -od, -ad, used to form adjectives from nouns, meaning "having, provided with, characterized by."