And there's no advantage in confusing a "canon" (which is defined by "official" exclusivity of one kind or another) with a "repertoire" (which is simply what a person or persons perform). Not that Jack intended to do so.

As for definitions, define "poetry" in twenty words or less? For starters, be sure your definition applies equally to the works of Shakespeare, William McGonagall, Homer, war chanters of the Amazon Basin, Whitman, rappers, Rod McKuen, writers of haiku, and first-year college students in an English class. And be sure it *excludes* any of the above (and anything else) that somebody might object to as "not poetry."

When you've done that to everyone's satisfaction try "folk music."

Such labels are very useful but they're simply not very precise unless made so for a particular discussion.

That would be a "stipulative" definition: "Let's stipulate for now that 'folk music' means blah blah blah so that we can discuss something intelligently."

An "ostensive" or "denotative" definition would be: "'Folk music' means stuff like X and Y and Z and A and B and so on. Get the picture?" (This often prompts the reply, "Where'd you get the idea that B folk music?!)

A "descriptive" definition describes what the term seems to mean in actual use. And that would mean that there's no single, comprehensive, objective, "canonical" definition of "folk music," "folk musician," etc. They mean rather different things to different people.