Episēmon (Greek , from epi- "on" plus sēma "sign"; plural: episēma) is a Greek word that can mean:
a distinguishing mark or symbol, also called parasēmon, especially in the following contexts: an ensign or figurehead on an ancient ship a characteristic symbol displayed on a shield, similar to a coat of arms a characteristic symbol stamped on an ancient coin the Greek letter Digamma, the numeral sign for "6" a generic term for all three supplementary Greek numeral signs (Digamma 6, Koppa 90, and Sampi 900) in the alphanumeric system of Greek numerals, or similar symbols in other scripts