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.