Final answer:
Uniformity in monetary denominations means that all bills of the same denomination within a currency system have the same purchasing power, a concept supported by the fungibility of money.
Step-by-step explanation:
Uniformity in monetary denominations is best described by the following phrase: All bills of any denomination have the same purchasing power. This means that within the same currency system, such as dollars or euros, all bills that are of the same denomination are interchangeable and have identical value. Economists typically consider money to be fungible, meaning each unit has equal value regardless of the situation. It's important to differentiate, however, that purchasing power can vary when compared internationally; hence the concept of purchasing power parity (PPP) is used to adjust for price level differences between countries.