Top definition
Pretty much the opposite of Mainstream music. Rarely, if ever, gets on the radio or top 40, and it's not usually well known to the general public. Also known as "Underground Music".
Non-mainstream music includes bands/artists such as Dream Theater, Porcupine Tree, Dรคlek, etc.
by 1729 February 15, 2009
Get the merch
Get the Non-Mainstream Music neck gaiter and mug.