micromagnetic

The story

1. Proto-Indo-European*mey-der.?
2. Ancient Greekμῑκρός (mīkrós)
3. Ancient Greekμῑκρο- (mīkro-)
4. Englishmicro-
5. Old Frenchmagnete
6. Ancient GreekΜάγνης (Mágnēs)
7. Ancient Greekμᾰ́γνης (mắgnēs)
8. Latinmagnēs
9. Middle Englishmagnete
10. Englishmagnet
11. Englishmagnetic
12. English todaymicromagnetic

From micro- + magnetic.