The word 'undressed' is a straightforward English formation built upon the core verb 'dress'. The verb 'dress' evolved from the idea of making something straight or correct (from Latin directus) to the specific act of arranging or adorning oneself with clothes. The Germanic negative prefix 'un-' is added to reverse this action, creating the sense of "not clothed". The past participle suffix '-ed' then solidifies this into an adjective describing the resulting state. Thus, the literal morpheme logic "not having been clothed" maps directly to the modern meaning of being without clothes, with a secondary application to food lacking its customary adornment of sauce.

Structure: un (not) + dress (to clothe) + ed (adjective suffix) - un: A prefix of Germanic origin (Old English) meaning "not" or "the opposite of". It functions as a negative particle. - dress: A verb of French and ultimately Latin origin, from Old French drecier "to arrange, set right", from Latin directus "straight, direct". In this compound, it carries the sense "to clothe or attire". - ed: A suffix of Germanic origin (Old English) used to form adjectives from verbs, indicating a state or condition.