anacoustic

The story

1. Proto-Indo-European*né
2. Proto-Indo-European*n̥-
3. Proto-Hellenic*ə-
4. Ancient Greekᾰ̓- (ă-)
5. Ancient Greekἀν- (an-)
6. Englishan-
7. Proto-Indo-European*h₂eḱ-
8. Proto-Indo-European*h₂ew-
9. Proto-Indo-European*h₂ṓws
10. Proto-Indo-European*h₂ḱh₂owsyéti
11. Proto-Hellenic*akóuhō
12. Ancient Greekἀκούω (akoúō)
13. Ancient Greekᾰ̓κουστῐκός (ăkoustĭkós)
14. Medieval Latinacousticus
15. Englishacoustic
16. English todayanacoustic

From an- + acoustic.