noun.
A system of recording or reproducing sound that uses two channels, each playing a portion of the original sound in such a way as to create the illusion of locating the sound at a particular position, each offset from the other, thereby more accurately imitating the location of the original sound when the recorded or reproduced sound is heard.
noun.
A device used for playing music, usually in the home, that reproduces sound using stereo.
adjective.
Of sound, music, etc, recorded in stereo.
adjective.
Of a pair of images: one depicting the view as would be seen from one eye and the other from the other eye, so that when viewed appropriately, they combine to give an impression of three dimensions.