nummus

thumb|right|150px|Nummi coins of the late reign of Anastasius I (emperor)|Anastasius I: on the left a 40-nummi coin ([[follis) and on the right a 5-nummi coin (pentanummium).]]

Nummus (. nummi) is a Latin word for various coins that was borrowed from Doric Greek noummos (; Classical Greek: , nómos). Originally referring to a specific style of coin used in Greek-speaking Southern Italy, the term nummus came to be used by the Late Republic for all coins generally and particularly as a synonym for the sestertius, then the standard unit of Roman accounting, and then in Late Antiquity as the formal name of the follis. It was used in this general sense in Early Modern English but is most commonly employed by modern numismatists as a catchall term for various low-value copper coins issued by the Roman and Byzantine empires during Late Antiquity.