What is the concept of total abandonment of a key within a piece of music known as?

The concept of total abandonment of a key within a piece of music is known as "atonality." Atonality refers to music that lacks a tonal center or key, meaning it does not adhere to traditional harmonic structures or scales. This approach often results in a more dissonant and complex sound, as it moves away from the established rules of tonal harmony. Atonality became particularly prominent in the early 20th century, with composers like Arnold Schoenberg leading its development.