'regress' originates from Latin, specifically the word 'regredi', where 're-' meant 'back' and 'gradi' meant 'to step'.

'regredi' transformed into the Old French word 'regresser', and eventually became the modern English word 'regress' through Middle English.

Initially, it meant 'to step back', but over time it evolved into its current meaning of 'to return to a previous state'.