diminution

Definition of Diminution in English :

1. decline, diminution

change toward something smaller or lower

2. diminution

the statement of a theme in notes of lesser duration (usually half the length of the original)

the act of decreasing or reducing something

WordNet Lexical Database for English. Princeton University. 2010.

Diminution

noun

1.

reduction; decrease

2. music

the presentation of the subject of a fugue, etc, in which the note values are reduced in length

Compare augmentation (sense 3)

noun

1.

a diminishing or being diminished; lessening; decrease

2. Music

variation of a theme by shortening, usually halving, the time value of the notes

n.

1.

a. The act or process of diminishing; a lessening or reduction.

b. The resulting reduction; decrease.

2. Music Statement of a theme in notes of lesser duration, usually one-half, of the original.