Vincent's NT Word Studies
19. Tribute-money (nomisma tou khnsou). Lit., the current coin of tribute, which was paid not in Jewish but in Roman money. See on ch. xvii. 25, tribute.A penny. See on Matt. xx. 2.
Robertson's NT Word Studies
22:19 {Tribute money} (to nomisma tou kensou). Knsos, Latin _census_, was a capitation tax or head-money, _tributum capitis_, for which silver denaria were struck, with the figure of Caesar and a superscription, e.g. "Tiberiou kaisaros" (McNeile). Nomisma is the Latin _numisma_ and occurs here only in the N.T., is common in the old Greek, from nomizw sanctioned by law or custom.