Q
- quarter tone: Half of a semitone; a pitch division not used in most Western music notation, except in some contemporary art music or experimental music. Quarter tones are used in Western popular music forms such as jazz and blues and in a variety of non-Western musical cultures.
- quasi (Latin and Italian): as if, almost, e.g. quasi recitativo like a recitative in an opera, or quasi una fantasia like a fantasia
Read more about this topic: Glossary Of Musical Terminology