The story
- Proto-Indo-European*né
- Proto-Indo-European*n̥-
- Proto-Germanic*un-
- Proto-West Germanic*un-
- Old Englishun-
- Middle Englishun-
- Englishun-
- Proto-Indo-European*h₂ent-
- Proto-Indo-European*h₂énts?
- Proto-Indo-European*h₂m̥bʰí
- Proto-Italic*amβi-
- Latinambi-
- Proto-Indo-European*h₂eǵ-
- Proto-Indo-European*h₂éǵeti
- Proto-Italic*agō
- Latinagō
- Latinambig(ō)
- Latinambiguu
- Englishambiguous
- Englishunambiguous
- Proto-Indo-European*leyg-
- Proto-Germanic*līką
- Englishun-
- Englishambiguous
- Englishambiguously
- English todayunambiguously
From unambiguous + -ly, or from un- + ambiguously.
Etymology from Wiktionary, CC BY-SA 4.0.