diminution

thumb|300px|Extract from Diego Ortiz's El Primo Libro ... Nel qual si tratta delle Glose depicting rhythm and generic intervals. Observe the diminution (i.e. division) process suggested by the composer, in reference to the rhythmic figures in the upper and lower musical parts. thumb|400px|A realization of the bottom line of the above Diego Ortiz extract in modern notation, completed with an arbitrarily chosen clef and a time signature.

In Western music and music theory, diminution (from Medieval Latin diminutio, alteration of Latin deminutio, decrease) has four distinct meanings. Diminution may be a form of embellishment in which a long note is divided into a series of shorter, usually melodic, values (also called "coloration"; Ger. Kolorieren). Diminution may also be the compositional device where a melody, theme or motif is presented in shorter note-values than were previously used. Diminution is also the term for the proportional shortening of the value of individual note-shapes in mensural notation, either by coloration or by a sign of proportion. A minor or perfect interval that is narrowed by a chromatic semitone is a diminished interval, and the process may be referred to as diminution (this, too, was sometimes referred to as "coloration").