I. ˈsü noun
( plural sous ˈsü(z))
Etymology: French, from Middle French, from Old French sol, solt, from Late Latin solidus, soldus solidus — more at solidus
1. : sol IV
2. : a 5-centime piece
3. : a smallest piece of money : penny , trifle
not a sou lost
II. abbreviation
south; southern