An attempt, in the late 1950's, to fuse jazz (usually bebop) with
classical music compositional techniques (usually those of 20th Century music). It was championed by Gunther Schuller, a "serious" composer, and John Lewis, the pianist of the Modern Jazz Quartet, but there were
antecedents in some works by George Russell and Bob Graettinger. The
antecedents were better, as were those who later, less self-consciously, did the same thing - like the musicians of the AACM.