"Ever wondered what a bodhisattva is? Or how to gaslight somebody? Then this site is for you! You're looking at an A-Z glossary of over 90 obscure words, people and places — all taken from the lyrics of Steely Dan songs."
While the Dan can't be classified as progressive, their music is certainly appreciated by many proggers (as I've noticed here on the Moon).
As the site's author explains, "Note that this is a dictionary of real-life people and places only. Becker and Fagen also concoct fictional names and locales for many of their songs, and because of their imaginary nature, it's impossible to pin down an exact definition. So this site doesn't attempt to explain words like Custerdome, battle apple, Steamer Heaven and many others. For ruminations on the meaning of such lyrics, visit the Fever Dreams site instead."
I hope you'll enjoy perusing this interesting website
http://www.steelydandictionary.com