Contraction
# Contraction

Contraction may refer to:

## Linguistics

* Contraction (grammar), a shortened word
* Poetic contraction, omission of letters for poetic reasons
* Elision, omission of sounds
   * Syncope (phonology), omission of sounds in a word
* Synalepha, merged syllables
   * Synaeresis, combined vowels
   * Crasis, merged vowels or diphthongs

## Mathematics and logic

* Contraction (operator theory), in operator theory, state of a bounded operator between normed vector spaces after suitable scaling
* Contraction hierarchies, in applied mathematics, a technique to speed up shortest-path routing
* Contraction mapping, a type of function on a metric space
* Edge contraction or vertex contraction, graph operations used in graph theory
* Tensor contraction, an operation on one or more tensors that arises from the natural pairing of a finite-dimensional vector space and its dual
* Left contraction and right contraction of multivectors in a geometric algebra, extensions of the inner product
* One of the rules of conditional independence, in probability
* Contraction (logic), a structural rule in proof theory

## Medicine

* Muscle contraction, the physiological condition of a muscle which generates tension (traction) at its origin and insertion
   * Uterine contraction, contraction of the uterus, such as during childbirth
* Contractility, the intrinsic ability of the heart/myocardium to contract
* Wound contraction, a stage in wound healing

## Other uses

* Contraction (economics), a general slowdown in economic activity; the opposite of economic expansion
* Contraction (physics), change in the volume of matter in response to a change in temperature
* Lanthanide contraction, the decrease in size of the ionic radius of lanthanide elements with their growing atomic number
* Contracted (film), a 2013 horror thriller film by Eric England and its sequel Contracted: Phase II (2015) which directed by Josh Forbes
