The name given by the Greeks to money put in the mouths of deceased persons to insure their passage over the river Styx.
Nashe, in Saffron Walden , 1596, says: "I hearing the fellow so forlorne...gaue him his Charons Naulum or ferry three half pence." See Juvenal (viii. 97), and Aristophanes, Frogs (270).
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)