Does underground music mean unreleased music?

Underground music is music unknown by the mainstream. Many genres started as underground, for example Punk and Metal. The Ramones were underground, when they started out. Hip Hop was an underground phenomenon before breaking into the mainstream. It is not radio music, it is often released by independent labels. So he is not right, but for underground artists music is often a hobby. Good underground bands are Within Temptation, Calabrese and, Tiger Army (possibly). UNderground music is very exciting, it is new kinds of music and new bands.