Atonality

noun

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.
3. the absence of a key; alternative to the diatonic system.
4. A style of music that is written without a key.
5. A passage written without a key.