Ton is the name of any one of several units of measure. It has a long history and has acquired several meanings and uses. Mainly it describes units of mass. Confusion can arise because ton can mean the long ton, which is 2,240 pounds (1016.05 kg) the short ton, which is 2,000 pounds (907.18 kg) the tonne, also called the metric ton, which is 1,000 kilograms or 1 megagram. Its original use as a measurement of volume has continued in the capacity of cargo ships and in terms such as the freight ton and a number of other units, ranging from in capacity. Recent specialized uses include the ton as a measure of energy and as a means of truck classification. It can also be used as a unit of energy, or in refrigeration as a unit of power, sometimes called a ton of refrigeration. Because the ton (of any system of measuring weight) is usually the heaviest unit named in colloquial speech, its name also has figurative uses, singular and plural, informally meaning a large amount or quantity, or to a great degree, as in "There's a ton of bees in this hive", "We have tons of homework", and "I love you a ton." History The ton is derived from the tun, the term applied to a cask of the largest capacity. This could contain a volume between , which could weigh around and occupy some of space. Units of mass/weight There are several similar units of mass or volume called the ton. Where precision is required the correct term should be used, as the difference between the short ton and the other common forms ("long" and "metric") is about 10%. However, when comparing between the metric and long tons, precision may not be as necessary as they differ by only 1.6%. The metric tonne is usually distinguished by its spelling when written, but in the US and UK it is pronounced the same as ton, hence is often spoken as "metric ton" when it is necessary to make the distinction. In the UK the final "e" of "tonne" can also be pronounced (),. In Australia, it is pronounced . In the United Kingdom, the (Imperial) ton is a statute measure, defined as 2,240 pounds (about ). In the United States and Canada, a ton is defined to be . Other units of mass/weight Deadweight ton (abbreviation 'DWT' or