tetrabasic

The story

1. Proto-Indo-European*kʷetwóres
2. Proto-Hellenic*kʷétwores
3. Ancient Greekτέσσᾰρες (téssăres)
4. Ancient Greekτετρᾰ- (tetră-)
5. Englishtetra-
6. Proto-Indo-European*gʷem-
7. Proto-Indo-European*gʷémtis
8. Proto-Hellenic*gʷə́tis
9. Ancient Greekβᾰ́σῐς (bắsĭs)
10. Latinbasis
11. Old Frenchbase
12. Middle Englishbase
13. Englishbase
14. Englishbasic
15. English todaytetrabasic

From tetra- + basic.