Merriam-Webster Collegiate Dictionary - contraction

 noun  Date: 15th century  1.  a. the action or process of contracting ; the state of being contracted  b. the shortening and thickening of a functioning muscle or muscle fiber  c. a reduction in business activity or growth  2. a shortening of a word, syllable, or word group by omission of a sound or letter; also a form produced by such shortening  • ~al adjective  • contractive adjective  • ~ary adjective