These units are now designated as historical and are no longer in common usage, being replaced by the metric system.

Usage of the unqualified term pound reflects the historical conflation of mass and weight.

The word 'pound' and its cognates ultimately derive from a borrowing into Proto-Germanic of the Latin expression libra pondo ('the weight measured in libra'), in which the word pondo is the ablative singular of the Latin noun pondus ('weight').

[7] The United States and the Commonwealth of Nations agreed upon common definitions for the pound and the yard.

Since 1 July 1959, the international avoirdupois pound (symbol lb) has been defined as exactly 0.45359237 kg.

In the United Kingdom, the process of metrication and European units of measurement directives were expected to eliminate the use of the pound and ounce, but in 2007 the European Commission abandoned the requirement for metric-only labelling on packaged goods there, and allowed for dual metric–imperial marking to continue indefinitely.

[23][24][b] In the United Kingdom, weights and measures have been defined by a long series of Acts of Parliament, the intention of which has been to regulate the sale of commodities.

Materials traded in the marketplace are quantified according to accepted units and standards in order to avoid fraud.

Quantifying devices used by traders (weights, weighing machines, containers of volumes, measures of length) are subject to official inspection, and penalties apply if they are fraudulent.

c. 49) marked a major overhaul of the British system of weights and measures, and the definition of the pound given there remained in force until the 1960s.

It has a groove about 0.34 inches (8.6 mm) from the top, to allow the cylinder to be lifted using an ivory fork.

c. 49) said that contracts worded in terms of metric units would be deemed by the courts to be made according to the Imperial units defined in the Act, and a table of metric equivalents was supplied so that the Imperial equivalents could be legally calculated.

The tower system ran concurrently with the avoirdupois and troy systems until the reign of Henry VIII, when a royal proclamation dated 1526 required that the troy pound be used for mint purposes instead of the tower pound.

[44] The Byzantines used a series of measurements known as pounds (Latin: libra, Ancient Greek: λίτρα, romanized: litra).

The most common was the logarikē litra (λογαρική λίτρα, "pound of account"), established by Constantine the Great in 309/310.

It formed the basis of the Byzantine monetary system, with one litra of gold equivalent to 72 solidi.

Due to its association with gold, it was also known as the chrysaphikē litra (χρυσαφική λίτρα, "gold pound") or thalassia litra (θαλάσσια λίτρα, "maritime pound"), but it could also be used as a measure of land, equalling a fortieth of the thalassios modios.

[45] The soualia litra was specifically used for weighing olive oil or wood, and corresponded to 4/5 of the logarikē or 256 g (9.0 oz).

The most important of these was the argyrikē litra (αργυρική λίτρα, "silver pound") of 333 g (11.7 oz), found in Trebizond and Cyprus, and probably of Arab origin.

For example, the measures and weights of the Habsburg monarchy were reformed in 1761 by Empress Maria Theresa of Austria.

[47] The unusually heavy Habsburg (civil) pound of 16 ounces was later defined in terms of 560.012 g (19.7538 oz).

Between 1803 and 1815, all German regions west of the River Rhine were under French control, organised in the departements: Roer, Sarre, Rhin-et-Moselle, and Mont-Tonnerre.

The Portuguese unit that corresponds to the pounds of different nations is the arrátel, equivalent to 16 ounces of Colonha, a variant of the Cologne standard.

In German, the term is Pfund, in French livre, in Dutch pond, in Spanish and Portuguese libra, in Italian libbra, and in Danish and Swedish pund.

Though not from the same linguistic origin, the Chinese jīn (斤, also known as the "catty") in mainland China has a modern definition of exactly 500 g (18 oz), divided into 10 liǎng (两).

Traditionally around 600 g (21 oz), the jin has been in use for more than two thousand years varying in exact value from one period to another, serving the same purpose as "pound" for the common-use measure of weight.

In Hong Kong, for the purposes of commerce and trade between Britain and Imperial China in the preceding centuries, three Chinese catties were equivalent to four British imperial pounds, defining one catty as 604.78982 g (21.333333 oz) in weight precisely.

[53] Smoothbore cannon and carronades are currently designated by the weight in imperial pounds of round solid iron shot of diameter to fit the barrel.

Before the introduction of the metric system, countries that produced their own artillery generally used their national pound for these designations.