'single-layer' originates from the combination of 'single' and 'layer', where 'single' meant 'one' and 'layer' referred to a 'stratum or level'.

'Single-layer' evolved from the Middle English word 'singel' and 'layere', eventually becoming the modern English term 'single-layer'.

Initially, it meant 'one level or stratum', and this meaning has largely remained the same in modern usage.