French franc. The franc (/fræŋk/; French: [fʁɑ̃]; sign: F or Fr), also commonly distinguished as the French franc (FF), was a currency of France. Between 1450 and 1999, it was the name of coins worth 1 livre tournois and it remained in common parlance as a term for this amount of money. It was reintroduced (in decimal form) in 1795.