The Apothecaries Unit is a system of measurement used in the medical and pharmaceutical fields. It is based on the avoirdupois system, which is the traditional system of weights and measures used in the United States. The two most common units of measurement in the Apothecaries Unit are the OUNCE (5 letters) and the DRAM (4 letters). An OUNCE is equal to 28.35 grams, while a DRAM is equal to 3.888 grams. This system of measurement is still used today in some parts of the world, particularly in the United Kingdom.