octapeptide

The story

1. Proto-Indo-European*oḱtṓw
2. Proto-Hellenic*oktṓ
3. Ancient Greekὀκτώ (oktṓ)
4. Ancient Greekὀκτᾰ- (oktă-)
5. Englishocta-
6. Proto-Indo-European*pekʷ-
7. Proto-Indo-European*pékʷ-ye-
8. Proto-Hellenic*pét͏̌t͏̌ō
9. Ancient Greekπέσσω (péssō)bf.
10. Ancient Greekπέπτω (péptō)
11. Ancient Greekπεπτόν (peptón)
12. GermanPepton
13. Englishpeptone
14. Proto-Indo-European*dʰeh₁-
15. GermanPepton
16. GermanPeptid
17. Englishpeptide
18. English todayoctapeptide

From octa- + peptide.