The avoirdupois system (; ; abbreviated avdp) is a system of weights (more properly, mass) based on a pound of 16 ounces. It is the everyday system of weight used in the United States and is still used to varying degrees in everyday life in the United Kingdom, Canada, the Republic of Ireland, and some other former British colonies despite the official adoption of the metric system. An alternative system of mass, the troy system, is generally used for precious materials. The modern definition of the avoirdupois pound is exactly  kilograms.