Constant structure
Appearance
In jazz, a constant structure is a chord progression consisting of three or more chords of the same type or quality[1]. Popularized by pianists Bill Evans and Herbie Hancock, the combination of functional and non-functional chords provides cohesiveness while producing a free and shifting tonal center[1].

For example, the progression Fmaj7-A♭maj7-D♭maj7-G♭maj7-C13sus[1] contains four major seventh chords (and one thirteenth chord), none of which are diatonic to the key of F major except the first.