(n): act of decreasing in length
(n): the process or result of becoming smaller or pressed together
(n): process or result of becoming less or smaller
(n): a word formed from two or more words by omitting or combining some sounds
(n): a unit of language that native speakers can identify
(n): the act of decreasing (something) in size or volume or quantity or scope
(n): the act of decreasing or reducing something
Contractions aren't necessary.