The follis (plural folles; Italian: follaro, Arabic: فلس, Fels) was a type of coin in the Roman and Byzantine traditions.
The term follis is used for a large bronze Roman coin denomination introduced by Diocletian in about 294. The term "nummus" is now thought to be the actual ancient term, but usage of "nummus" has not caught on. Web site: Describing Ancient Coins – Roman Imperial Coins – the Late Empire. Ancient Greek and Roman Coins. live . https://web.archive.org/web/20061006081242/http://dougsmith.ancients.info/voc5.html . 6 October 2006. 6 November 2023. ). At first the follis weighed about 10 grams and was about 4% silver, with a thin layer of silver on the surface. Over the next decades it declined both in size and in silver content.
The word follis means bag (usually made of leather) in Latin, and there is evidence that this term was used in antiquity for a sealed bag containing a specific amount of coinage. It has also been suggested that the coin was named Follis because of the ancient Greek word "φολίς" meaning a thin layer of metal (cf. Latin folium, "leaf") which covers the surface of various objects, since originally, this coin had a thin layer of silver on top. The 'follis' of Diocletian, despite efforts to enforce prices with the Edict on Maximum Prices (301), was revalued and reduced as time passed. By the time of Constantine the Great, it was smaller and barely contained any silver. A series of Constantinian bronzes was introduced in the mid-4th century, although the specific denominations are unclear and debated by historians and numismatists. They are referred to as AE1, AE2, AE3 and AE4, with the first being the largest (near 27 mm) and the last the smallest (averaging 15 mm) in diameter. Namely:
Large hoards of folles have been discovered all across the Roman empire. For example, in Seaton Down, Devon, England, near the site of a second- to third-century Roman villa and fortifications, 22,888 folles were found in 2013.[1] Fourth century folles represent the largest category of coin finds in the United Kingdom.[2] Between 30,000 and 50,000 exceptionally well-preserved folles from the first half of the fourth century were discovered in the sea near the north-east shore of Sardinia in 2023.[3]
The term "follis" is used for the large bronze coin denomination (40 nummi) introduced in 498, with the coinage reform of Anastasius, which included a series of bronze denominations with their values marked in Greek numerals.
The fals (a corruption of follis) was a bronze coin issued by the Umayyad and Abbasid caliphates beginning in the late 8th century, initially as imitations of the Byzantine follis.