Diminution

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"). 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").

Diminution is a form of embellishment or melodic in which a long note or a series of long notes is divided into shorter, usually melodic, values, as in the similar practices of breaking or division in England, passaggio in Italy, double in France and glosas or diferencias in Spain. Thoroughly documented in written sources of the 16th, 17th and early 18th centuries, with a remarkable flowering in Venice from about 1580–1620, diminution is an integral aspect of modern performance practice. Donington describes the consequences of failing to add "necessary figuration" as "disastrous".

...
Wikipedia