The Italian word for "pound," libbra, derives from the Latin libra, with which the Romans designated both the weighing instrument and the basic unit of the weight system. The associated verb librare meant "to weigh."

The pound is an ancient unit of weight used in many countries and localities, but with different values. Still used informally in a few Italian regions (roughly equivalent to 1/3 of a kilogram), the pound was fairly widespread before the introduction of the kilogram: its value ranged from 350 to 500 grams depending on the country. The Tuscan pound, for example, was equal to 348 grams. The avoirdupois pound—one of the three systems of weights still in use in Britain and the Commonwealth countries—is defined as the mass of the platinum prototype kept at the Board of Trade in London. Its metric equivalent is 0453.59243 kilograms. The pound served as a unit of measurement for all types of goods except stones, precious metals, and medicines.