idiom

The story

1. Ancient Greek · derived fromἰδίωμα“a peculiarity, property, a peculiar phraseology, idiom”
2. Middle French · derived fromidiome
3. English todayidiom

From Middle French idiome, and its source, Late Latin idioma, from Ancient Greek ἰδίωμα (idíōma, “a peculiarity, property, a peculiar phraseology, idiom”), from ἰδιοῦσθαι (idioûsthai, “to make one's own, appropriate to oneself”), from ἴδιος (ídios, “one's own, pertaining to oneself, private, personal, peculiar, separate”). By surface analysis, idi- + -om.