Where does “fatidus” come from?

fatidus (Late Latin) comes from Latin fatuus, from Latin fātus, from Latin for, from Proto-Italic fāōr, from Proto-Indo-European bʰéh₂ti — to speak, to be talking.

Ancestry of “fatidus”, step by step

fatidus traces back through two separate lines of ancestry.

via Latin fatuus

Step	Language	Word	Meaning
1	Latin	fatuus	foolish, silly, simple; stupid; insipid,...
2	Latin	fātus	spoken, said, told, foretold, related, predicted; having or had spoken, etc
3	Latin	for	"defective"; I speak, talk, say
4	Proto-Italic	fāōr	speak
5	Proto-Indo-European	bʰéh₂ti	to speak, to be talking

via Latin vapidus

Step	Language	Word	Meaning
1	Latin	vapidus	that has emitted steam or vapor; flat or vapid;...
2	Latin	-idus	tending to
3	Proto-Italic	*-iðos	—

Every word from Proto-Indo-European bʰéh₂ti →Every word from Proto-Italic fāōr →Every word from Latin for →