'anciency' originates from Middle English, specifically the word 'auncien', where 'auncien' meant 'ancient' or 'old'.

'auncien' changed from Old French word 'ancien' and eventually became the modern English word 'ancient', from which 'anciency' is derived as a noun form.

Initially, it meant 'the state of being old or ancient', and this meaning has largely remained the same in modern usage.