The story
- Proto-Indo-European*tréyes
- Proto-Indo-European*tri-
- Proto-Italic*tri-
- Latintri-
- Englishtri-
- 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 todaytrifunctional
From tri- + functional.
Etymology from Wiktionary, CC BY-SA 4.0.