aconceptual

The story

1. Proto-Indo-European*né
2. Proto-Indo-European*n̥-
3. Proto-Hellenic*ə-
4. Ancient Greekἀ- (a-)
5. Englisha-
6. Proto-Indo-European*ḱe?
7. Proto-Indo-European*ḱóm
8. Proto-Italic*kom
9. Proto-Italic*kom-
10. Latincon-
11. Proto-Indo-European*kap-
12. Proto-Indo-European*kapyéti
13. Proto-Italic*kapjō
14. Latincapiō
15. Ancient Greekσῠλλᾰμβᾰ́νω (sŭllămbắnō)
16. Latinconcipiō
17. Latinconceptus
18. Proto-Indo-European*h₂el-
19. Proto-Indo-European*h₂élisder.?
20. Medieval Latinconceptuālis
21. Englishconceptual
22. English todayaconceptual

From a- + conceptual.