'permanently-built' originates from the combination of 'permanent' and 'build', where 'permanent' comes from Latin 'permanens', meaning 'enduring', and 'build' from Old English 'byldan', meaning 'to construct'.

'permanens' transformed into the Middle English 'permanent', and 'byldan' evolved into the modern English 'build', eventually forming the compound 'permanently-built'.

Initially, 'permanent' meant 'enduring', and 'build' meant 'to construct', which together evolved to describe structures meant to last indefinitely.