diminution

noun

1. (countable, uncountable)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.”

   “Cold is usually shapeless, I suppose, extending over large spaces equally, or with gradual diminution.”

   “Scenic illusions such as those caused by the haze, or the apparent diminution of scale where everything was enormous, intrigued Dutton.”

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