The pound is a unit of mass (acceptable for use as weight on Earth) and is part of the imperial system of units. It has the symbol lb.
Not to be confused with a number of other definitions, the most common is international avoirdupois pound. The avoirdupois pound is defined as exactly 0.45359237 kilograms and is divided into 16 avoirdupois ounces.
One of the most common uses of the pound is in measuring the mass / weight of human beings or animals. When introduced, sports athletes such as boxers or wrestlers are described by their weight in pounds before any other characteristic as it helps people visualise how big / powerful they are.
The unit pounds originated from the Roman ‘libra’ (hence the abbreviated ‘lb’). The libra, which is Latin for scales or balance, was an ancient Roman unit used to measure mass and was equivalent to approximately 328.9 grams. The libra was originally split into 12 ounces (or unciae).
Random fact: Some cannons, such as the Smoothbore cannon, are based on the imperial pounds of circular solid iron balls of the diameters that fit the barrels. For example, a cannon that fires 12-pound ball is called a twelve-pounder.
The stone is a unit of mass (acceptable for use as weight on Earth) and is part of the imperial system of units. It has the symbol st.
In historical times actual stones were used as weights, a practice that was adopted worldwide for more than 2000 years.
In Europe, up until the 19th century, the stone was frequently used in the trade industry to measure weight. Each country had their own weight of the stone which varied between regions and what was being traded. As a result, the metric system was adopted in most European countries.
In England in 1389 a stone of wool was characterized as weighing fourteen pounds (lbs). Despite the fact that a stone of different materials would not necessarily weigh exactly fourteen pounds, the stone became accepted as weighing exactly 14 lbs.
The stone is also used in sports. In horse racing it is used to describe the weight that a horse has to carry. The weight includes the jockey as well as overweight, penalties and allowances. It is also used to express human bodyweight in sports such as boxing and wrestling.
In the UK and Ireland people will often use stone and pounds (e.g. 11 st 5 lbs) to express their weight. In contrast people in the United States will most commonly use just pounds (eg. 159 lbs).
Although the Stone has not been recognised in the UK as a unit of weight since 1985, it is still the most common and popular way of expressing human weight in this country.