Avant-garde music is a subjective term that can be used in different ways. In a popular, large sense it refers to any popular music which is thought to be ahead of its time, e.g. containing innovative elements or fusing different genres.

Historically speaking, musicologists primarily use the term "avant-garde music" for the radical post-1945 tendencies of a modernist style in several genres of art music after the death of Anton Webern in 1945. In the 1950s the term avant-garde music was mostly associated with serial music. Today the term may be used to refer to any other post-1945 tendency of modernist music not definable as experimental music, though sometimes including a type of experimental music characterized by the rejection of the tonal language.