quadrennium/kwɑˈdrɛniəm/EtymologyFrom Late Latin quadrennium, from Latin quadriennium, from quadriennis (“4-year”) + -ium (suffix forming abstract nouns).quadrennium means A period of 4 years, particularly (historical) the sets of four years in the ancient Egyptian and Greek calendars. Lexicurio rates it Sui generis — a strength score of 87 out of 100.nounA period of 4 years, particularly (historical) the sets of four years in the ancient Egyptian and Greek calendars.