The Latin word asper originally meant "rough", but had gradually acquired the connotation of "fresh" and, especially when referring to silver, "white", by the imperial period. It acquired a technical meaning in the 12th century, when the Byzantines began to refer to the billon trachy coin, which was issued in a blanched state, as aspron. The same name was also sometimes applied to the contemporary electrum trachy as well.
The name re-appears in the 14th–15th centuries as a generic name for silver coinage, such as the Byzantine doukatopoulon or the Turkish akçe. The 15th century account books of the Venetian merchant-banker Giacomo Badoer lists several cities and governments that coined aspers, which included Trebizond, Caffa, Simisso (or Samsun), Tana, and Rhodes.
- Grierson 1991, p. 211.
- Cecile Morrison, "Coin Usage and Exchange Rates in Badoer’s Libro dei Conti", Dumbarton Oaks Papers, 55 (2001), pp. 217-245