quinquennium
noun
quin·quen·ni·um kwin-ˈkwe-nē-əm 
kwiŋ-
plural quinquenniums or quinquennia kwin-ˈkwe-nē-ə
kwiŋ-
: a period of five years
Word History
Etymology
Latin, from quinque five + annus year — more at five, annual
First Known Use
1621, in the meaning defined above