'blithely' originates from Old English, specifically the word 'blīðe,' where 'blīðe' meant 'joyous, kind, cheerful.'

'blīðe' transformed into the Middle English word 'blithe,' and eventually became the modern English word 'blithely.'

Initially, it meant 'joyous or kind,' but over time it evolved into its current meaning of 'in a carefree or joyous manner.'