'disconfirm' originates from Modern English, formed by adding the prefix 'dis-' (meaning 'not' or 'the opposite of') to the verb 'confirm', which ultimately comes from Latin 'confirmare'.

'confirm' comes from Latin 'confirmare' ('to make firm; establish'), passed into Old French as 'confirmer' and Middle English as 'confirmen' before becoming the modern English 'confirm'. 'disconfirm' developed in modern English by applying the productive negative prefix 'dis-' to 'confirm'.

In Latin 'confirmare' initially meant 'to make firm or strengthen'; over time 'confirm' shifted to mean 'establish as true or certain', and 'disconfirm' came to mean 'to show that something is not established as true' (to negate or refute confirmation).