'belatedly' originates from the English word 'belated', which is derived from the prefix 'be-' meaning 'thoroughly' and the word 'late', meaning 'after the expected time'.

'belated' evolved from the Old English word 'læte', which meant 'slow' or 'late', and eventually became the modern English word 'belated'.

Initially, it meant 'after the expected time', and this meaning has largely remained the same in modern usage.