Where does “ventennio” come from?

ventennio (Italian) comes from Italian -ennio, from Latin -ennium, from Latin -ennis, from Latin annus, from Proto-Italic atnos, from Proto-Indo-European h₂et-no-, from Proto-Indo-European h₂et- — grass.

ventennio (Italian): a period of twenty years

Definitions

a period of twenty years

Ancestry of “ventennio”, step by step

Step	Language	Word	Meaning
1	Italian	-ennio	forms nouns from numbers, meaning "period of ~ years"
2	Latin	-ennium	forming periods of years
3	Latin	-ennis	—
4	Latin	annus	year; time; season
5	Proto-Italic	atnos	year
6	Proto-Indo-European	h₂et-no-	—
7	Proto-Indo-European	h₂et-	grass

Every word from Proto-Indo-European h₂et- →