Webster's Revised Unabridged Dictionary · 1913

Acoustic

Acoustic (#; 277) , adjective

[French acoustique, Greek {not transcribed} relating to hearing, from {not transcribed} to hear.]

Pertaining to the sense of hearing, the organs of hearing, or the science of sounds; auditory.
Collocations (3)
Acoustic duct , the auditory duct, or external passage of the ear.
Acoustic telegraph , a telegraph making audible signals; a telephone.
Acoustic vessels , brazen tubes or vessels, shaped like a bell, used in ancient theaters to propel the voices of the actors, so as to render them audible to a great distance.

Acoustic , noun

A medicine or agent to assist hearing.