adj. & n.
adj. 1 relating to sound or the sense of hearing. 2 (of a musical instrument, gramophone, or recording) not having electrical amplification (acoustic guitar). 3 (of building materials) used for soundproofing or modifying sound. 4 Mil. (of a mine) that can be exploded by sound waves transmitted under water.
n. 1 (usu. in pl.) the properties or qualities (esp. of a room or hall etc.) in transmitting sound (good acoustics; a poor acoustic). 2 (in pl.; usu. treated as sing.) the science of sound (acoustics is not widely taught). acoustic coupler Computing a modem which converts digital signals into audible signals and vice versa, so that the former can be transmitted and received over telephone lines. acoustical adj. acoustically adv.
[ Gk akoustikos f. akouo hear ]