magnetomechanically

The story

1. Ancient GreekΜάγνης (Mágnēs)
2. Ancient Greekμᾰ́γνης (mắgnēs)
3. Old Frenchmagnete
4. Ancient Greekμᾰ́γνης (mắgnēs)
5. Latinmagnēs
6. Middle Englishmagnete
7. Englishmagnet
8. Englishmagnet-
9. Englishmagneto-
10. Proto-Indo-European*megʰ-der.?
11. Ancient Greekμηχανή (mēkhanḗ)
12. Ancient Greekμηχανικός (mēkhanikós)
13. Latinmēchanicus
14. Old Frenchmecanique
15. Middle Englishmechanic
16. Proto-Indo-European*h₂el-
17. Proto-Indo-European*h₂élisder.?
18. Middle Englishmechanical
19. Englishmechanical
20. Proto-Indo-European*leyg-
21. Proto-Germanic*līką
22. Englishmechanically
23. English todaymagnetomechanically

From magneto- + mechanically or magnetomechanics + -ally.