adj. also a·cous·ti·cal (-stĭ-kəl)
1. Of or relating to sound, the sense of hearing, or the science of sound.
a. Designed to carry sound or to aid in hearing.
b. Designed to absorb or control sound: acoustic tile.
a. Of or being an instrument that does not produce or enhance sound electronically: an acoustic guitar; an acoustic bass.
b. Being a performance that features such instruments: opened the show with an acoustic set.
An acoustic instrument.
[Greek akoustikos, pertaining to hearing, from akouein, to hear; see kous- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.