'unadorned' originates from the prefix 'un-' meaning 'not' and the word 'adorned' from Latin 'adornare', where 'ad-' meant 'to' and 'ornare' meant 'to equip or furnish'.

'adornare' transformed into the Old French word 'adourner', and eventually became the modern English word 'adorn'. The prefix 'un-' was added to form 'unadorned'.

Initially, 'adorn' meant 'to equip or furnish', and 'unadorned' has consistently meant 'not decorated or plain'.