'eternally-maintained' originates from the combination of 'eternal' and 'maintain', where 'eternal' comes from Latin 'aeternalis', meaning 'everlasting', and 'maintain' from Latin 'manutenere', meaning 'to hold in the hand'.

'eternally-maintained' evolved from the Middle English 'eternal' and 'maintain', eventually forming the modern English compound adjective 'eternally-maintained'.

Initially, 'eternal' meant 'without end', and 'maintain' meant 'to keep in a certain state'. Together, they evolved to mean 'kept in a perpetual state'.