A slug is a unit of mass in a weight-based system of measures, most notably within the British Imperial measurement system and the United States customary measures system). It is a derived unit of mass, defined as a mass that is accelerated by 1 ft/s2 when a net force of one pound (lbf) is exerted on it). The slug is part of a subset of units known as the gravitational FPS system, one of several such specialized systems of mechanical units developed in the late 19th and early 20th century).
One slug is a mass equal to 32.1740 lb (14.59390 kg) based on standard gravity, the international foot, and the avoirdupois pound). At the Earths surface, an object with a mass of 1 slug weighs approximately 32.2 lbf or 143 N). The name "slug" was coined before 1900 by British physicist Arthur Mason Worthington, but it did not see any significant use until decades later. It is derived from the meaning "solid block of metal" (cf. "slug" fake coin or "slug" projectile), not from the slug mollusc).
