What is "piedfort"

n. An unusually thick coin, often exactly twice the normal weight and thickness of other coins.

A piedfort (French pronunciation: pee-ay-for or pyay-for; English pronunciation: peed-fert or peed-fort) is an unusually thick coin, often exactly twice the normal weight and thickness of other coins of the same diameter and pattern. Piedforts are not normally circulated, and are only struck for presentation purposes by mint officials (such as patterns), or for collectors, dignitaries, and other VIPs. Piedfort is commonly misspelled as "piefort".