What is the term for a group of notes that clash when played together?

The term "Cluster" refers to a group of notes that clash when played together, typically consisting of adjacent pitches. Clusters create a dissonant sound due to the close intervals between the notes, resulting in a tense and complex texture. This can be used effectively in various musical genres to evoke specific emotional responses or enhance musical expression.

In contrast, a "Chord" is generally a harmonious combination of three or more notes, typically forming consonant sounds when played together. A "Scale" is a sequence of notes in a specific order, usually following a specific pattern of whole and half steps, and does not imply clashing. A "Triad" is a specific type of chord consisting of three notes, typically formed by stacking thirds, which also tends to create consonance rather than dissonance. Thus, the correct terminology for a group of notes that clash is indeed a cluster.