'reinforce' originates from Old French, specifically the word 'reinforsser,' where 're-' meant 'again' and 'enforcier' meant 'to strengthen.'

'reinforsser' transformed into the Middle English word 'reinforsen,' and eventually became the modern English word 'reinforce.'

Initially, it meant 'to strengthen again,' but over time it evolved into its current meaning of 'to make stronger or more pronounced.'