'disbelieve' originates from the prefix 'dis-' meaning 'not' and the word 'believe' from Old English 'belȳfan', where 'be-' meant 'about' and 'lȳfan' meant 'to allow'.

'belȳfan' transformed into the Middle English word 'bileven', and eventually became the modern English word 'believe'. The prefix 'dis-' was added to form 'disbelieve'.

Initially, 'believe' meant 'to allow or trust', and with the prefix 'dis-', it evolved to mean 'not to trust or accept as true'.