The quadrille was one of the most popular ball-room dances of the 19th century, generally in a brisk duple metre.
Glossary of Musical Terms
Divisions of the tone smaller than a semitone are occasionally found in art-music, particularly in the 20th century. Quarter-tones occur in the solo violin part of the Second Violin Concerto of Bel Bartk.
A quartet is a composition for four players or the name for a group of four players.
A quintet is a composition for five players or the name for a group of five players.
A quodlibet (Latin: what you please) is a light-hearted composition generally containing a combination of well known tunes. There is an example in Johann Sebastian Bach's Goldberg Variations, where the composer combines the theme of the variations with two popular songs of the time.