Contraction may refer to:
In physiology:
- Muscle contraction, one that occurs when a muscle fiber lengthens or shortens
- Uterine contraction, contraction of the uterus, such as during childbirth
- Contraction, a stage in wound healing
In linguistics:
- Poetic contraction, the omission of letters in a word for poetic reasons
- Synalepha, merging of two syllables of adjacent words
- Elision, the loss of a sound
- Syncope (phonetics), the loss of sounds inside a word
- Contraction (grammar), the shortening of a word or words by loss of a sound or sounds
- Synaeresis, the pronunciation of two vowels as a diphthong
- Crasis, contraction of two vowels into one monophthong
- Elision, the loss of a sound
In science:
- Lanthanoid contraction, the decrease in size of the ionic radius of lanthanide elements with their growing atomic number (series of Rare Earth Elements (REE) in the Mendeleev Table)
- The reverse of thermal expansion
In mathematics:
- Contraction mapping, in mathematics, a type of function on a metric space
- Contraction (operator theory)
- Edge contraction or vertex contraction, graph operations used in graph theory
- Tensor contraction in tensor theory
- Contraction (conditional independence), in probability, one of the rules of conditional independence
Other:
- Economic contraction or recession, a reversal of economic growth; the opposite of economic expansion
- A structural rule in proof theory Further information: idempotency of entailment
- In sports, the (sometimes forced) elimination of a team. The opposite of expansion. Example: the elimination of several teams after the Canadian Football League's failed attempt to expand into the United States in the early 1990s.