palaeomagnetic

The story

1. Proto-Indo-European*kʷelh₁-der.?
2. Ancient Greekπάλαι (pálai)
3. Ancient Greekπᾰλαιός (pălaiós)
4. Englishpaleo-
5. Englishpalaeo-
6. Old Frenchmagnete
7. Ancient GreekΜάγνης (Mágnēs)
8. Ancient Greekμᾰ́γνης (mắgnēs)
9. Latinmagnēs
10. Middle Englishmagnete
11. Englishmagnet
12. Englishmagnetic
13. English todaypalaeomagnetic

From palaeo- + magnetic.