The story
- Proto-Indo-European*dwóh₁
- Proto-Indo-European*dwi-
- Proto-Hellenic*dwi-
- Ancient Greekδῐ- (dĭ-)
- Latindi-
- Englishdi-
- Proto-Indo-European*bʰewg-
- Proto-Indo-European*bʰunégti
- Proto-Italic*fungōr
- Latinfungor
- Latinfūnctiō
- Old Frenchfonction
- Middle Frenchfunction
- Englishfunction
- Proto-Indo-European*h₂el-
- Proto-Indo-European*h₂élisder.?
- Englishfunctional
- English todaydifunctional
From di- + functional.
Etymology from Wiktionary, CC BY-SA 4.0.