idiolect

The story

1. Proto-Indo-European*swé
2. Proto-Indo-European*swéd-yo-s
3. Proto-Hellenic*hwédios
4. Ancient Greekῐ̓́δῐος (ĭ́dĭos)
5. Englishidio-
6. Proto-Indo-European*dwóh₁
7. Proto-Indo-European*trísinflu.
8. Proto-Indo-European*dwís
9. Ancient Greekδιά (diá)
10. Ancient Greekδῐᾰ- (dĭă-)
11. Proto-Indo-European*leǵ-
12. Proto-Indo-European*léǵ-e-ti
13. Proto-Hellenic*légō
14. Ancient Greekλέγω (légō)
15. Ancient Greekδιαλέγομαι (dialégomai)
16. Ancient Greekδῐᾰ́λεκτος (dĭắlektos)
17. Latindialecto
18. Middle Frenchdialecte
19. Englishdialectbf.
20. English todayidiolect

From idio- + -lect.