cast coins
As opposed to struck, these coins were produced by pouring melted metal in a mould.

countermark
A small letter, monogram or other device punched on the face of a coin already struck, usually with the object of changing its value.

follis
(pl. folles) A Latin word originally meaning a purse, but used in the Byzantine period for the largest denomination of copper coin, initially worth 40 nummi.

Half-follis (20 nummi)
A denomination of copper coin, worth half a follis or 20 nummi.

mint-mark
Letters or symbols placed on a coin to indicate where it was struck. In the Byzantine period they are usually a shortened version of the mint name.

nummus
A Latin term meaning originally ‘coin’. In the Early Byzantine period the term was normally applied to the smallest copper coin, 1/40th of the follis, which served as the base of the accounting system.

obverse
The face of the coin which bears the more important device. Due to ambiguities that sometimes exist, many numismatists prefer to use the term for the side struck by the lower (anvil) die.

pentanummium, pl. -a
Bronze or copper coin worth 5 nummi.

reverse
The back view of a coin where the issuing authority is usually inscribed.

solidus
The standard Byzantine gold coin, weighing 24 carats or 4.55g, introduced by Constantine the Great.

type
The main design on each face of a coin. By extension, a class of coins united by a common design.

value mark
Letters or symbols placed on a coin to indicate its value.