The compound adjective 'well-proportioned' is a relatively modern English formation. Its core, 'proportion', entered English via Old French from Latin proportio, which itself combined pro- ("for") and portio ("portion, share"), conveying the idea of a harmonious relation between parts. The adverbial modifier 'well', of ancient Germanic origin, intensifies this concept to mean "in a good or satisfactory manner." The suffix '-ed' then transforms the noun phrase into an adjective, completing the logical evolution from the literal idea of "having parts in good relation" to the modern aesthetic sense of being balanced and pleasing in shape or form.

Structure: well (adverb) + proportion (noun) + ed (adjective suffix) - well: From Old English wel, meaning "in a good manner, satisfactorily." It functions as an intensifying adverb modifying the adjective. - proportion: From Latin proportio(n-), from pro ("for, in relation to") + portio ("share, part"). It is the core noun meaning a balanced relation of parts. - ed: A suffix of Old English origin used to form adjectives from nouns, meaning "having, provided with."