'equivalence' originates from Latin, specifically the word 'aequivalentia,' where 'aequi-' meant 'equal' and 'valentia' meant 'strength or worth.'

'aequivalentia' transformed into the Old French word 'equivalence,' and eventually became the modern English word 'equivalence' through Middle English.

Initially, it meant 'equal strength or worth,' but over time it evolved into its current meaning of 'state of being equal or equivalent.'