<p><strong>Adjective</strong></p><ul><li>pertaining to the sense or organs of hearing, to sound, or to the science of sound.</li><li>(of a building material) designed for controlling sound.</li><li>Music. of, relating to, or being a musical instrument whose sound is not electrically enhanced or modified.</li><li>arranged for or made up of such instruments: an acoustic solo; an acoustic group.</li></ul><p><strong>Noun</strong></p><ul><li>Obsolete. a remedy for deafness or imperfect hearing.</li></ul>