Stone
The stone is an imperial unit of mass equal to 14 pounds or approximately 6.35 kilograms. It is primarily used in the United Kingdom and Ireland for expressing human body weight.
History
The stone has been used as a unit of weight since at least the 14th century. Its value varied by region and commodity before being standardized at 14 pounds in 1835 by the Weights and Measures Act. While no longer an official SI unit, it remains widely used for body weight in British culture.