The phrase "rate of exchange" typically refers to the value of one currency compared to another. However, there are several synonyms for this phrase that can be used interchangeably. One possible synonym is "currency exchange rate," which is commonly used in financial contexts. Another synonym is "exchange rate," which can refer to both the value of currencies and the process of exchanging them. "Foreign exchange rate" is another option, particularly when discussing the value of currencies in international markets. Overall, these synonyms can help writers and speakers convey the same concept using different phrasing.