the compound adjective 'youthful-looking' is a modern english formation that combines two established elements to describe appearance. the first part, 'youthful', derives from the old english noun 'geoguth', meaning young people collectively, which itself evolved from the proto-germanic 'jugunth-', related to concepts of youth and vigor. the addition of the adjectival suffix '-ful' creates a word meaning "characteristic of youth." this is then attached to the present participle 'looking', from old english 'lōcian', a verb of west germanic origin meaning to use one's sight or to have a certain appearance. the compound's logic is transparent: it literally means "having the appearance characteristic of youth," a descriptive term often used in contexts of personal description where someone's visage belies their chronological age.

Structure: youthful (adjective) + looking (present participle) youthful: from middle english 'youthe' (the state or quality of being young) + the suffix '-ful' (full of, characterized by). origin: old english 'geoguth' (young people) + '-ful' (old english '-full'). looking: from the present participle of the verb 'look', from old english 'lōcian' (to see, gaze, appear).