• (noun): The absence of a key; alternative to the diatonic system.
    Synonyms: atonality

Some articles on atonalism:

Keith Burstein - Musical Approach and Philosophy (including Theory of "Super Tonality")
... approach was informed by the culture of atonalism in which he was educated at the Royal College of Music, and his early compositions were written in the atonal style ... I suddenly saw that atonalism was a dead end ... as "neo-romantic", he has stated that his education in atonalism has informed his musical approach ...