In order to provide a more in-depth definition for many of the terms below I have provided links to the definitions which are available at Wikipedia.
DEMIX - to separate various sounds from a mix, typically vocals and musical instruments
DIGITALLY CONSTRUCTED STEREO (DCS) - a term coined by Andy Balogh to refer to stereo mixes created by copying, pasting, looping, etc. sounds from within a mono source to use them elsewhere within a new mix to give the illusion of a stereo mix.
DIGITALLY EXTRACTED STEREO (DES) - a term I coined in 2000 to describe stereo mixes created from mono sources through the use of digital signal processing software, including spectral editing, sound source separation, and related processes.
MONO (the shortened version of monophonic and monaural - for convenience I will use the term mono on this website by default)
PSEUDOSTEREO or PSEUDO-STEREO - a term applied to stereo mixes created to give the illusion of spaciousness from mono sources
SIMULATED STEREO - see also PSEUDOSTEREO
SOUND SOURCE SEPARATION (also referred to as AUDIO SOURCE SEPARATION)
SPECTRAL EDITOR - an audio editor which allows the editing of sound in a spectrogram which shows time on the x axis, frequency on the y axis, and audio level as brightness. The audio may also be color coded to indicate loudness or other characteristics.
STEREO (the shortened version of STEREOPHONIC - for convenience I will use the term stereo on this website by default)
UNMIX - see DEMIX
UPMIX - refers to stereo or surround sound mixes created from mono source material and surround sound mixes created from mono and stereo source material