indiction

英 [ɪn'dɪkʃ(ə)n] 美

indiction (n.): late 14c., "period of fifteen years," a chronological unit of the Romans, originally for taxation purposes, fixed by Constantine and reckoned from Sept. 1, 312; it was still in use in the Middle Ages. From Latin indictionem (nominative indictio) "declaration, appointment," noun of action from past participle stem of indicere (see indictive).