'unwalled' originates from the prefix 'un-' meaning 'not' and the word 'wall', which comes from Old English 'weall', meaning 'a structure enclosing an area'.

'weall' transformed into the Middle English word 'wall', and eventually became the modern English word 'wall'. The prefix 'un-' was added to form 'unwalled'.

Initially, 'wall' meant 'a structure enclosing an area', and 'unwalled' has consistently meant 'not enclosed by walls'.