Where does “Fabius” come from?

Fabius is a Latin cognomen derived from Latin faba meaning bean, ultimately from Proto-Indo-European bʰabʰ- with the agent suffix -yós.

Ancestry of “Fabius”, step by step

Step	Language	Word	Meaning
1	Latin	Fabius	of or pertaining to the gens Fabia
2	Latin	-ius	forming adjectives from nouns; nominative neuter...
3	Proto-Italic	-jōs	Forms comparative adjectives
4	Proto-Indo-European	-yós	Creates adjectives from noun or verb stems

Fabius — Etymology, Origin & Word History | Etymology Explorer