'antient' originates from Old French, specifically the word 'ancien', ultimately from Latin roots (see below) where Latin 'ante' meant 'before' or 'long ago'.

'antient' changed from Old French 'ancien' and Middle English forms such as 'auncient', and eventually existed alongside the modern spelling 'ancient' (with 'antient' remaining as an archaic variant).

Initially it meant 'old' or 'from before' in the sense of 'belonging to an earlier time'; over time the core meaning remained 'very old', while the spelling 'antient' became archaic and replaced in common use by 'ancient'.