'fearfully' originates from the Old English word 'fǣrful', where 'fǣr' meant 'sudden danger or peril'.

'fǣrful' transformed into the Middle English word 'ferful', and eventually became the modern English word 'fearful'.

Initially, it meant 'full of fear or danger', but over time it evolved into its current meaning of 'in a manner that shows fear or anxiety'.