A "slug," in the context of mass, is a unit of measurement primarily used in the United States customary and British imperial systems. It is not a widely used unit and is considered somewhat archaic. The slug is used to measure mass and is defined as the mass that accelerates at a rate of one foot per second squared (1 ft/s²) when a force of one pound-force (1 lbf) is applied to it. In other words, a slug is the mass that results in an acceleration of 1 ft/s² when a force of 1 lbf is applied to it.
n the United States, the term "stone" is not a commonly used unit of measurement for weight or mass in everyday contexts. Instead, the United States primarily uses pounds (lbs) to measure weight. One pound is equal to approximately 0.0714 stones.
However, the "stone" is a traditional unit of weight used more commonly in the United Kingdom and some other countries, but it is not part of the standard metric system.
1 stone (UK) = 14 pounds (lbs)
So, when you encounter the term "stone" in the context of weight or mass in the United States, it's typically used informally or in specialized contexts where individuals may be familiar with this unit of measurement due to cultural or international exposure.