follis

[fol-is] /ˈfɒl ɪs/
noun, plural folles
[fol-eez] /ˈfɒl iz/ (Show IPA)
1.
a bag of copper or bronze coins with a fixed weight, used as money of account in the later Roman Empire.
2.
a silver-plated copper coin of ancient Rome, first issued by Diocletian.
3.
a copper coin of the Eastern Roman Empire, a.d. c500.
Origin
1880-85; < Late Latin; compare Latin follis bag, purse