quinquennĭum, ii, n. [quinquennis],
a period of five years , five years (class.): CENSORES MAGISTRATVM QVINQVENNIVM HABENTO, Cic. Leg. 3, 3, 7: tria quinquennia, i. e. fifteen years , Ov. M. 4, 292: duo, id. ib. 12, 584.
quīnquennium ī, n quinquennius, a period of five years, five years : quinqueni imperium prorogare:...
An Elementary Latin Dictionary
·noun Space of five years. ...
Webster's Dictionary of the English Language