n.
In music, the absence of functional harmony as a primary structural element.
Probably originally a pejorative term applied to music of extreme chromaticism , it has become the most widely used descriptive term for 20th-century music whose connection with tonality is difficult to hear. Arnold Schoenberg and his students Alban Berg and Anton Webern are regarded as the seminal atonal composers; the serialism of their later work is often distinguished from their earlier "free atonality."