'adequacy' originates from Latin, specifically the word 'adaequatio,' where 'ad-' meant 'to' and 'aequus' meant 'equal.'

'adaequatio' transformed into the French word 'adéquation,' and eventually became the modern English word 'adequacy' through Middle English.

Initially, it meant 'to make equal or sufficient,' but over time it evolved into its current meaning of 'sufficiency for a particular purpose.'