Noun

(en noun)

A reversible reduction in size.

(economics) A period of economic decline or negative growth.

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

(biology) A shortening of a muscle when it is used.

(medicine) A strong and often painful shortening of the uterine muscles prior to or during childbirth.

(linguistics) 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 .

(English orthography) A word with omitted letters replaced by an apostrophe, usually resulting from the above process.

"Don't" is a contraction of "do not."

(medicine) Contracting a disease.

The contraction of AIDS from toilet seats is extremely rare.

(phonetics) Syncope, the loss of sounds from within a word.

The acquisition of something, generally negative.

Our contraction of debt in this quarter has reduced our ability to attract investors.

(medicine) A distinct stage of wound healing, wherein the wound edges are gradually pulled together.

Noun

(en noun)

an increase in density; the act of compressing, or the state of being compressed; compaction

the cycle of an internal combustion engine during which the fuel and air mixture is compressed

(computing) the process by which data is compressed

* {{quote-web

, year = 2011 , author = Marcelo A. Montemurro & Damián H. Zanette , title = Universal Entropy of Word Ordering Across Linguistic Families , site = PLoS ONE , url = http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0019875 , accessdate = 2012-09-26}}

Due to the presence of long-range correlations in language [21], [22] it is not possible to compute accurate measures of the entropy by estimating block probabilities directly. More efficient nonparametric methods that work even in the presence of long-range correlations are based on the property that the entropy of a sequence is a lower bound to any lossless compressed version of it [15]. Thus, in principle, it is possible to estimate the entropy of a sequence by finding its length after being compressed by an optimal algorithm. In our analysis, we used an efficient entropy estimator derived from the Lempel-Ziv compression algorithm that converges to the entropy [19], [23], [24], and shows a robust performance when applied to correlated sequences [25] (see Materials and Methods).

(music) the electronic process by which any sound's gain is automatically controlled

(astronomy) the deviation of a heavenly body from a spherical form