Where does “flayau” come from?

flayau (Old French) comes from Latin flagellum, from Latin -lus, from Proto-Italic -elos, from Proto-Indo-European -e-lós, from Proto-Indo-European -lós — Forms agent nouns from verbal roots.

Ancestry of “flayau”, step by step

Step	Language	Word	Meaning
1	Latin	flagellum	whip, lash, scourge; whip for driving animals;...
2	Latin	-lus	Alternative form of -ulus; diminutive suffix
3	Proto-Italic	-elos	Forms desubstantival and deadjectival diminutive nouns
4	Proto-Indo-European	-e-lós	—
5	Proto-Indo-European	-lós	Forms agent nouns from verbal roots

Every word from Proto-Indo-European -lós →Every word from Latin -lus →Every word from Latin flagellum →