Where does “quinquenio” come from?
quinquenio (Spanish) comes from Latin quīnquennium, from Latin quinquennis, from Latin annus, from Proto-Italic atnos, from Proto-Indo-European h₂et-no-, from Proto-Indo-European h₂et- — grass.
quinquenio (Spanish): lustrum, quinquennium
Ancestry of “quinquenio”, step by step