'unaproned' originates from English, specifically from the prefix 'un-' (Old English 'un-') combined with the word 'apron', where 'un-' meant 'not' and 'apron' ultimately comes from Old French 'naperon' (from Latin 'mappa' meaning 'cloth').

'apron' in Middle English came by rebracketing from Old French 'naperon' (seen as 'a napron' → 'an apron'); 'unaproned' is formed later by adding the negative prefix 'un-' and the adjectival/past participle suffix '-ed' to this noun.

Initially it literally described the absence of an apron or cloth covering; over time the compound has retained that basic sense and can also be used figuratively to mean 'not protected' or 'not covered'.