Pronunciation: (ok"si-tō'sun),[key] —n. 1. Biochem.a polypeptide hormone, produced by the posterior lobe of the pituitary gland, that stimulates contraction of the smooth muscle of the uterus.
2. Pharm.a commercial form of this substance, obtained from beef and hog pituitary glands or esp. by synthesis, and used chiefly in obstetrics to induce labor and to control postnatal hemorrhage.