'atonalism' originates from English, formed by the prefix 'a-' (from Greek 'a-' meaning 'not') + 'tonal' (from 'tone') + the suffix '-ism' (from Greek/Latin '-ismos'/'-ismus' indicating doctrine or practice).

'atonal' was coined in the late 19th to early 20th century to describe music lacking a tonal center; 'atonal' + '-ism' produced 'atonalism' to name the practice or movement (notably used for early 20th-century composers such as Schoenberg).

Initially it referred specifically to the absence of a tonal center in a piece of music; over time it also came to denote a broader movement or approach to composition and, more generally, the concept of rejecting traditional tonality.