The siliqua is the modern name given to small, thin, Roman silver coins produced from 4th century and later. When the coins were in circulation, the Latin word siliqua was a unit of weight defined as one-twentyfourth of the weight of a Roman solidus (coin)

Solidus (coin)

The solidus was originally a gold coin issued by the Romans, and a weight measure for gold more generally, corresponding to 4.5 grams.-Roman and Byzantine coinage:...

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The term siliqua comes from the siliqua graeca, the seed of the carob tree, which in the Roman weight system is equivalent to 1/6 of a scruple (1/1728 of a Roman pound or about 0.19 grams).

The term has been applied in modern times to the various silver coins on the premise that the coins were valued at 1/24 of the gold solidus

Solidus (coin)

The solidus was originally a gold coin issued by the Romans, and a weight measure for gold more generally, corresponding to 4.5 grams.-Roman and Byzantine coinage:...

 (which weighed 1/72nd of a Roman pound) and therefore represented a siliqua of gold in value. Since gold was worth about 14 times as much as silver in ancient Rome, such a silver coin would have a theoretical weight

Weight

In science and engineering, the weight of an object is the force on the object due to gravity. Its magnitude , often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus:...

 of 2.7 grams. There is little historical evidence to support this premise. This has not prevented the term from being applied today to silver coins issued by Constantine, which initially weighed 3.4 grams, or the later silver coin of Constantius II

Constantius II

Constantius II , was Roman Emperor from 337 to 361. The second son of Constantine I and Fausta, he ascended to the throne with his brothers Constantine II and Constans upon their father's death....

, which weighed about 2.2 grams and 18mm, and is sometimes called a "light" or "reduced" siliqua to differentiate it. The term is one of convenience as no name for these coins is indicated by contemporary sources. Thin silver coins to the 7th century which weigh about 2 to 3 grams are known as siliqua by numismatic convention.

See also

• Roman currency
  Roman currency
  The Roman currency during most of the Roman Republic and the western half of the Roman Empire consisted of coins including the aureus , the denarius , the sestertius , the dupondius , and the as...
  
  
• Hoxne Hoard
  Hoxne Hoard
  The Hoxne Hoard is the largest hoard of late Roman silver and gold discovered in Britain, and the largest collection of gold and silver coins of the fourth and fifth century found anywhere within the Roman Empire...
  
  , a hoard of 14,212 silver siliquae dating from the early 5th century.