'relax' originates from Latin, specifically the word 'relaxare', where 're-' meant 'again/back' and 'laxare' (from 'laxus') meant 'loose'.

'relax' changed from Late Latin 'relaxare' (and past participle 'relaxatus'), passed through Old French/Late Latin forms such as 'relaxer', and eventually became the modern English word 'relax'.

Initially, it meant 'to loosen or release', but over time it evolved into its current meaning of 'to make less tense; to rest or reduce strictness'.