1. The absence of a tonal center and of harmonies derived from a diatonic scale corresponding to such a center; lack of tonality.
2. A style of composition that lacks such a tonal center and its derived harmonies.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.