In music and music theory, a bichord or polychord consists of two or more chords, one on top of the other. In shorthand they are written with the top chord above a line and the bottom chord below, for example F upon C: .
Polychords: E minor, E♭ major, E♭ major, and D major over D minor.Play (help·info)
In the polychords in the image above, the first might suggest a thirteenth chord, the second may suggest a D minor ninth chord with upper extensions, but the octave separation of the 3rd makes the suggestion of two independent triads a minor ninth apart even more likely, and the fourth is a split-third chord.
^Haerle, Dan (1982). The Jazz Language: A Theory Text for Jazz Composition and Improvisation, p. 30. ISBN978-0-7604-0014-2. "The term polychord literally means many (poly) chords. In actual practice, a polychord is usually a combination of only two chords which creates a more complex sound."
^Guy Capuzzo, Tom Dempsey (2006). Theory for the Contemporary Guitarist, p. 76. ISBN978-0-7390-3838-3. "A bichord (other-wise known as a polychord) consists of two triads played together."
^Edward Shanaphy, Joseph Knowlton (1990). The Do It Yourself Handbook for Keyboard Playing, p. 62. ISBN978-0-943748-00-9. "A polychord is nothing more than the playing of two chords at the same time."
^ abPolicastro, Michael A. (1999). Understanding How to Build Guitar Chords and Arpeggios, p. 168. ISBN978-0-7866-4443-8.
^Reisberg, Horace (1975). "The Vertical Dimension in Twentieth Century Music", Aspects of Twentieth-Century Music, p. 336. Wittlich, Gary (ed.). Englewood Cliffs, New Jersey: Prentice-Hall. ISBN0-13-049346-5.