Where does “idiōma” come from?

idiōma (Latin) comes from Ancient Greek ἰδίωμα, from Ancient Greek ἰδιοῦσθαι, from Ancient Greek ἴδιος, from Proto-Hellenic *hwédios.

Ancestry of “idiōma”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ἰδίωμα	peculiarity, specific property, unique feature;...
2	Ancient Greek	ἰδιοῦσθαι	to make one's own, appropriate to oneself
3	Ancient Greek	ἴδιος	pertaining to self, that is, one's own; private;...
4	Proto-Hellenic	*hwédios	—