Mainstream is a term most often applied in the arts—i.e., music, literature, and performance—to

• something that is not out of the ordinary or unusual;
• something that is familiar to the masses;
• something that belongs to an identifiable genre, such as detective fiction, horror, fantasy, or science fiction.

Hollywood movies are mainstream.

See also normal, conformism.

Antonyms

• avant-garde
• eclectic (although an improper use of the term)
• fringe
• off-beat
• special (in the context of education, where it is often used as a verb)
• underground (culture)

Related:

• blogstream