late 14c., "action of making a contract" (especially of marriage), also "action of shrinking or shortening," from Old French contraction (13c.), or directly from Latin contractionem (nominative contractio), noun of action from past participle stem of contrahere (see contract (n.)). Meaning "action of acquiring (a disease) is from c.1600. Grammatical sense is from 1706; meaning "a contracted word or words" is from 1755. Contractions of the uterus in labor of childbirth attested from 1962.
contraction con·trac·tion (kən-trāk'shən)
The act of contracting or the state of being contracted.
The shortening and thickening of functioning muscle or muscle fiber.
The shortening and thickening of a muscle for the purpose of exerting force on or causing movement of a body part. See more at muscle.
A word produced by running two or more words together and leaving out some of the letters or sounds. For example, isn't is a contraction of is not.
Note: An apostrophe is generally used in contractions to show where letters or sounds have been left out.