inambiguous

The story

1. Proto-Indo-European*né
2. Proto-Indo-European*n̥-
3. Proto-Italic*n̥-
4. Latinin-
5. Middle Englishin-
6. Englishin-
7. Proto-Indo-European*h₂ent-
8. Proto-Indo-European*h₂énts?
9. Proto-Indo-European*h₂m̥bʰí
10. Proto-Italic*amβi-
11. Latinambi-
12. Proto-Indo-European*h₂eǵ-
13. Proto-Indo-European*h₂éǵeti
14. Proto-Italic*agō
15. Latinagō
16. Latinambig(ō)
17. Latinambiguu
18. Englishambiguous
19. English todayinambiguous

From in- + ambiguous.