tetraboron

The story

1. Proto-Indo-European*kʷetwóres
2. Proto-Hellenic*kʷétwores
3. Ancient Greekτέσσᾰρες (téssăres)
4. Ancient Greekτετρᾰ- (tetră-)
5. Englishtetra-
6. Middle Persian*bōrag
7. Arabicبَوْرَق (bawraq)
8. Medieval Latinborax
9. Anglo-Normanboreis
10. Middle Englishboras
11. Englishborax
12. Englishboro-
13. Proto-Indo-European*kerh₃-der.?
14. Latincarbōnem
15. Frenchcarbone
16. Englishcarbonbf.
17. Englishboron
18. English todaytetraboron

From tetra- + boron.