'regretfully' originates from the word 'regretful', which comes from the Old French word 'regret', where 're-' meant 'again' and 'greter' meant 'to weep'.

'regret' changed from the Old French word 'regret' and eventually became the modern English word 'regret'.

Initially, it meant 'to weep again', but over time it evolved into its current meaning of 'feeling sorrow or remorse'.