A quarter-tone is a musical interval that is halfway between a semitone and a whole tone. This type of interval is commonly used in non-Western musical traditions and has become increasingly popular in contemporary classical music. There are several synonyms for quarter-tone, including microtone, half-sharp, and alternate tuning. Microtone refers to any musical interval that is smaller than a semitone, so it can be used to describe quarter-tone intervals. Half-sharp is another term that is sometimes used to describe quarter-tone intervals, as it suggests an interval that is halfway between a sharp and a natural note. Finally, alternate tuning can also refer to a tuning system that includes quarter-tone intervals.