But (as I understand it) the “definition” of side chaining is basically combining a dry signal with a heavily compressed signal.

Scott, what you’re talking about is called parallel compression…I think

Side chaining is when an external audio signal is used to trigger the compressor. Like when ‘ducking’ is used in radio, for example. The disc jockey’s mic is sent to the compressor’s side chain while the music is also sent to the compressor. The disc jockey’s voice triggers the compressor to turn down the music.