The Collaborative International Dictionary of English v.0.48:
atonality \atonality\ n. the absence of a key; alternative to the diatonic system. Syn: atonalism. [WordNet 1.5]WordNet (r) 3.0 (2006):
atonality n 1: the absence of a key; alternative to the diatonic system [syn: atonality, atonalism] [ant: key, tonality]