The words we use for music, who made them, and what they leave out.
Everything below is language we use to talk about sound — because it lets us build tools that do something useful, and because enough people share it that we can be understood.
None of it is a finding about what music is. These words were invented by particular people, in particular places, to describe the music in front of them. They travelled well and they left things out. Both of those are worth knowing.
So each entry says what we mean, whose vocabulary it is, and what it does not settle. Where our own tools had to commit to one system in order to compute anything at all, we say so plainly — that is the last section.
How the app actually uses the word — the operational definition, not the textbook one.
Who coined it and roughly when. A term with an author is visibly a choice.
The edge of the term: what it cannot describe, or describes badly. Never left blank.
Every entry in every section carries those three. If we could not fill the third one honestly, we left the entry out.