Contraction

noun

1. A reversible reduction in size.
2. A period of economic decline or negative growth.

   "The country's economic contraction was caused by high oil prices."

3. A shortening of a muscle when it is used.
4. A strong and often painful shortening of the uterine muscles prior to or during childbirth.
5. A process whereby one or more sounds of a free morpheme (a word) are lost or reduced, such that it becomes a bound morpheme (a clitic) that attaches phonologically to an adjacent word.

   "In English didn't, that's, and wanna, the endings -n't, -'s, and -a arose by contraction."