The aspron (Greek: ἄσπρον), from Latin asper, was a late Byzantine name for silver or silver-alloy coins. The Latin word asper originally meant "rough", but had gradually acquired the connotation of "fresh" or "freshly minted", i.e. not worn smooth by use, 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 an aspron. The same name was also sometimes applied to the contemporary electrum trachy as well.