Where does “idiota” come from?

idiota (Latin) comes from Ancient Greek ἰδιώτης, from Ancient Greek ἴδιος, from Proto-Hellenic *hwédios.

Ancestry of “idiota”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ἰδιώτης	a private person, one not engaged in public...
2	Ancient Greek	ἴδιος	pertaining to self, that is, one's own; private;...
3	Proto-Hellenic	*hwédios	—

idiota — Etymology, Origin & Word History | Etymology Explorer