tamoxifen

The story

1. Proto-Indo-European*terh₂-
2. Proto-Indo-European*térh₂t
3. Proto-Indo-European*tr̥h₂ónts
4. Proto-Indo-European*tr̥h₂n̥ts
5. Proto-Italic*trāns
6. Proto-Italic*trāns-
7. Latintrans-
8. Englisht(rans)-
9. Egyptianjmn
10. Ancient GreekᾸ̓́μμων (Ắmmōn)
11. LatinAmmōn
12. Latinammoniacus
13. Englishammonia
14. Englisham(ine)
15. Proto-Indo-European*h₂eḱ-der.?
16. Ancient Greekὀξῠ́ς (oxŭ́s)
17. Englishoxy-
18. Proto-Indo-European*bʰeh₂-
19. Proto-Indo-European*bʰh₂nyéti
20. Proto-Hellenic*pʰáňňō
21. Ancient Greekφαίνω (phaínō)
22. Frenchphéno-
23. Proto-Indo-European*swel-der.?
24. Ancient Greekῡ̔́λη (hū́lē)
25. Frenchphényle
26. Englishphen(yl)
27. English todaytamoxifen

From t(rans)- + am(ine) + oxy- + phen(yl).