From Late Latin 'cambiare' (to barter), probably from Celtic for 'crooked' — the original concept was bending off course.
The act or instance of making or becoming different; an alteration or modification in state, form, or quality.
From Old French 'changier' (to change, to exchange, to alter), from Late Latin 'cambiāre' (to exchange, to barter), probably of Celtic origin — compare Old Irish 'camm' (crooked, bent) and Welsh 'cam' (crooked). The underlying metaphor may be 'to bend' or 'to turn,' suggesting change as a deviation from a straight course. The same root produced
The 'change' you receive from a purchase and the 'change' meaning alteration come from the same word — the original meaning was 'exchange,' and getting your change was receiving the exchange balance. The foreign currency 'bureau de change' preserves this older exchange meaning directly.