Experimental music is a term introduced by composer John Cagein 1955. Cage defined "an experimental action is one the outcome of which is not foreseen" (Cage 1961, 39), and he was specifically interested in completed works that performed an unpredictable action (Mauceri 1997, 197) In a broader sense, it has come to mean any music that challenges the commonly accepted notions of what music is. Avant-garde music is another term for it. David Cope describes experimental music as that, "which represents a refusal to accept the status quo" (Cope, 1997, 222).

Michael Nyman (1974) uses the term "experimental" to describe the work of American composers^[1] (John Cage, Christian Wolff, Earle Brown, Meredith Monk, Malcolm Goldstein, Morton Feldman, Terry Riley, La Monte Young, Philip Glass, John Cale, Steve Reich, etc.) as opposed to the European avant-garde at the time (Karlheinz Stockhausen, Pierre Boulez, Iannis Xenakis). The word "experimental" in the former cases "is apt, providing it is understood not as descriptive of an act to be later judged in terms of success or failure, but simply as of an act the outcome of which is unknown" (Cage 1961, 13).