What are notes that move by the interval of a semitone called?

Notes that move by the interval of a semitone are referred to as chromatic notes. This term describes the use of semitonal movement within music, often resulting in a rich, colorful sound. The chromatic scale, which consists of all twelve pitches within an octave, utilizes these semitone intervals, making it fundamental in various musical genres, particularly in Western classical music and jazz.

The concept of chromaticism allows composers and musicians to explore tension and resolution in music. Because chromatic notes are not restricted to the tonal center established by the diatonic scale, their usage provides greater harmonic and melodic flexibility.

In contrast, terms like diatonic refer to notes that fit within a specific scale or key, whole tone indicates intervals of a whole step (two semitones), and quarter tone refers to intervals smaller than a semitone found in some world music and avant-garde compositions. Understanding these distinctions reinforces the importance of intervallic relationships within music theory and composition.