Generally, the term post-bop is taken to mean jazz from the mid-sixties onward that assimilates influence from hard bop, modal jazz, the avant-garde, and free jazz, without necessarily being immediately identifiable as any of the above. The term is a fairly recent coinage and (like "Northern soul") was not in common use while the genre was active.
According to musicologist Jeremy Yudkin, post-bop did not follow "the conventions of bop or the apparently formless freedom of the new jazz". He wrote in his definition of the subgenre:
Forms, tempos, and meters are freer, all the compositions are new, and the band members themselves are featured composers ... [A]n approach that is abstract and intense in the extreme, with space created for rhythmic and coloristic independence of the drummer—an approach that incorporated modal and chordal harmonies, flexible form, structured choruses, melodic variation, and free improvisation."