'non-reimbursement' originates from the prefix 'non-' meaning 'not' and the word 'reimbursement', which comes from the Latin 'reimbursare', meaning 'to repay'.

'reimbursare' transformed into the Old French word 'reembourser', and eventually became the modern English word 'reimburse'. The prefix 'non-' was added to indicate the absence of reimbursement.

Initially, 'reimbursare' meant 'to repay', and the prefix 'non-' was added to indicate the opposite, leading to the current meaning of 'not being repaid'.