Noun
free jazz (uncountable)
(music, jazz) A form of jazz music of the 1950s and 1960s that attempted to overcome existing limitations and conventions, often by discarding features such as fixed chord changes or tempos.
I don't want to do free jazz! Because free jazz - which is the musical equivalent of free marketeering - isn't actually free at all. It's just constrained by what your muscles can do. Brian Eno
Free jazz allowed for radical improvised departures from the harmonic and rhythmic material of the composition for instance, by permitting performers to ignore conventional repeating song-structures. Source: Internet