Where does “fossō” come from?

fossō (Latin) comes from Latin fodiō, from Proto-Indo-European bʰod- — to pierce, dig.

Ancestry of “fossō”, step by step

Step	Language	Word	Meaning
1	Latin	fodiō	—
2	Proto-Indo-European	bʰod-	to pierce, dig

fossō — Etymology, Origin & Word History | Etymology Explorer