'bareheaded' originates from Modern English, specifically a compound of 'bare' and 'head' (with the adjectival suffix '-ed'), where 'bare' meant 'uncovered' and 'head' meant 'head'.

'bare' comes from Old English 'bær' meaning 'naked' and 'head' comes from Old English 'heafod'; the compound form 'bare-headed' is attested from Middle English and developed into the modern single-word form 'bareheaded'.

Initially, it meant 'with the head uncovered', and over time it has retained that meaning as 'without a hat or other head covering'.