polyacoustics

The story

1. Proto-Indo-European*pleh₁-
2. Proto-Indo-European*polh₁ús
3. Ancient Greekπολῠ́ς (polŭ́s)
4. Englishpoly-
5. Proto-Indo-European*h₂eḱ-
6. Proto-Indo-European*h₂ew-
7. Proto-Indo-European*h₂ṓws
8. Proto-Indo-European*h₂ḱh₂owsyéti
9. Proto-Hellenic*akóuhō
10. Ancient Greekἀκούω (akoúō)
11. Ancient Greekᾰ̓κουστῐκός (ăkoustĭkós)
12. Medieval Latinacousticus
13. Englishacoustic
14. Englishacoustics
15. English todaypolyacoustics

From poly- + acoustics.