:This article deals with the unit of force. For the unit of mass see Pound (mass). The pound-force or simply pound (abbreviations: lb, lbf, or lbf) is a unit of force. Definitions The pound-force is approximately equal to the gravitational force exerted on a mass of one avoirdupois pound on the surface of Earth. Since the 18th century, the unit has been used in low-precision measurements, for which small changes in Earth's gravity (which varies from place to place by up to half a percent) can… (More on Pound-force)