sou

The sou is a historical unit of currency that was used in the Kingdom of France during the Middle Ages and the early modern period. It functioned as a small, widely circulated unit within the livre tournois monetary system and appears in many accounting records and coinages of the time.

Etymology and value relations: the term sou derives from the Latin solidus and came into medieval French usage as a low-value coin and unit of account. In the standard system, 1 livre tournois was divided into 20 sous, and each sou was further subdivided into 12 deniers. The exact coin’s value and the metal composition varied over time and by region, with copper or low-grade silver coins commonly circulating as sous.

Usage and historical context: the sou served both as a coin and as a unit of account in daily commerce, taxes, and wages. It coexisted with other subunits in the broader livre tournois framework (and in related regional systems). Over the centuries, the value and production of sou coins fluctuated, reflecting monetary reforms, economic conditions, and minting practices of different rulers.

End of official use and legacy: in 1795, as part of the French Revolution’s monetary reforms, the old livre system was replaced by the decimal franc, and the sou ceased to function as an official unit. The name survives in modern French idiom as a figure of speech for a small amount of money, as in “pas un sou.” Numismatists and economic historians study sou coins to illuminate medieval and early modern French finances.