Keith Burgess-Jackson, J.D., Ph.D.

First, there was music; then there was folk or popular music; and now there is classical music.

Addendum: My friend Jeff pointed out, correctly, that the word "classical," like the word "democratic," is ambiguous. It is used as both an adjective ("a democratic form of government") and a proper name ("the Democratic Party"). When used as a proper name, it is capitalized ("Classical music"). The term "classical music" is a retronym only when "classical" is being used as an adjective. See here (meanings 3a and 3b) for the two uses/senses of the word.