exchange: [14] Like change, exchange comes ultimately from Latin cambīre ‘barter’. In postclassical times this had the prefix ex- added to it, here functioning as an indicator of ‘change’, producing late Latin *excambiāre. In Old French this became eschangier (whence modern French échanger), which English acquired via Anglo- Norman eschaunge. A 15th-century reversion to the original Latin spelling of the prefix produced modern English exchange. => change
