diminution

noun

Etymology: From Middle English diminucioun, from Anglo-Norman diminuciun, Old French diminucion, from Latin dīminūtiō.

1. A lessening, decrease or reduction.

   “The new emission standards have produced a measurable diminution in air pollution.”

   “Another part, feeling a diminution of confidence in him, still hope that the general tenor of his conduct will be essentially right.”

2. The act or process of making diminutive.
3. a compositional technique where the composer shortens the melody by shortening its note values.