A quartertone is a musical interval that is half the size of a semitone. There are a few different synonyms that can be used to refer to this interval or pitch range, depending on the context. One commonly used term is microtone, which encompasses all intervals smaller than a semitone. Other synonyms for quartertones include quarter-step (which is often used in Eastern music systems), half-sharp, and half-flat. In some contexts, the term "in between" may be used to describe quartertones, as they fall somewhere between the standard semitones of Western music. Regardless of the term used, quartertones add a unique and nuanced dimension to musical compositions and performances.