astrogeometry

The story

1. Proto-Indo-European*h₂eHs-
2. Proto-Indo-European*h₂stḗr
3. Proto-Hellenic*astḗr
4. Ancient Greekἀστήρ (astḗr)
5. Ancient Greekᾰ̓́στρον (ắstron)
6. Englishastro-
7. Proto-Hellenic*gaya
8. Ancient Greekγαῖᾰ (gaîă)clip.
9. Ancient Greekγῆ (gê)
10. Ancient Greekγεω- (geō-)
11. Proto-Indo-European*med-
12. Proto-Indo-European*meh₁-
13. Ancient Greekμέτρον (métron)
14. Ancient Greekγεωμετρῐ́ᾱ (geōmetrĭ́ā)
15. Latingeōmetria
16. Old Frenchgeometrie
17. Middle Englishgemetry
18. Englishgeometry
19. English todayastrogeometry

From astro- + geometry.