A person who listens exclusively or almost exclusively to progressive music, including progressive rock and progressive metal. Often spotted wearing space-themed or geometric band tees while drumming odd time signatures on their lap.
John: I just got back from that Animals As Leaders concert! It was amazing! Now i'm gonna go home and listen to some Dream Theater and Rush. I can't wait to headbang some 13/8 rhythms.
Bob: Wow, John, I didn't know music fans got that pretentious! Get out of here, you stupid progfag.