Where does “quinquennially” come from?
quinquennially (English) comes from English quinquennial, from Latin quinquennalis, from Latin quinquennis, from Latin annus, from Proto-Italic atnos, from Proto-Indo-European h₂et-no-, from Proto-Indo-European h₂et- — grass.
quinquennially (English): Every five years
Ancestry of “quinquennially”, step by step