atonality

[ey-toh-nal-i-tee] /ˌeɪ toʊˈnæl ɪ ti/
noun, Music.
1.
the absence of key or tonal center.
2.
an atonal principle or style of composition.
Origin
1920-25; atonal + -ity
British Dictionary definitions for atonality

atonality

/ˌeɪtəʊˈnælɪtɪ; ˌæ-/
noun
1.
absence of or disregard for an established musical key in a composition
2.
the principles of composition embodying this and providing a radical alternative to the diatonic system
Compare tonality
Word Origin and History for atonality
n.

1950; see atonal + -ity.