'believer' originates from Old English, specifically the word 'belȳfan,' where 'be-' meant 'about' and 'lȳfan' meant 'to allow or permit.'

'belȳfan' transformed into the Middle English word 'bileven,' and eventually became the modern English word 'believe,' from which 'believer' is derived.

Initially, it meant 'to allow or permit,' but over time it evolved into its current meaning of 'to have faith or confidence in something.'