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

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


  • 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.