1. Units used to measure the mass of any substance; except precious gems and metals, and drugs.

It includes the pound, short and long tons, ounce, and dram.

2. A system of units of mass based on the pound (0.45 kilograms), which consists of 16 ounces (each of 16 drams) or 7,000 grains (each equal to 65 milligrams).