noun (n)

• (physiology) a shortening or tensing of a part or organ (especially of a muscle or muscle fiber)(noun.act)

  Synonym:
  muscle contraction, muscular contraction
  

  source: wordnet30
• the process or result of becoming smaller or pressed together(noun.event)

  Example:
  The contraction of a gas on cooling.
  

  Synonym:
  compression, condensation
  

  source: wordnet30
• a word formed from two or more words by omitting or combining some sounds(noun.communication)

  Example:
  `won't' is a contraction of `will not'.
  `o'clock' is a contraction of `of the clock'.
  

  source: wordnet30
• the act of decreasing (something) in size or volume or quantity or scope(noun.act)

  Antonym:
  enlargement, expansion
  

  source: wordnet30
• The act or process of contracting, shortening, or shrinking; the state of being contracted; as, contraction of the heart, of the pupil of the eye, or of a tendon; the contraction produced by cold.(noun)

  source: webster1913