'vary' originates from Latin, specifically the word 'variare', where the root 'vari-' meant 'different' or 'to change'.

'vary' changed from Old French 'varier' and Middle English forms such as 'varien' and eventually became the modern English word 'vary'.

Initially, it meant 'to make different or to change', but over time it evolved into its current meanings of 'to differ' or 'to change in amount, degree, or nature'.