Meaning

noun reproducer in which two microphones feed two or more loudspeakers to give a three-dimensional effect to the sound

noun two photographs taken from slightly different angles that appear three-dimensional when viewed together

adjective designating sound transmission from two sources through two channels

originA shortened form of stereotype, stereoscope or stereophonic, all originally derived, via stereo-, from Ancient Greek στερεός (stereós, “solid”).

Etymology from Wiktionary, CC BY-SA 3.0