Pronunciation: (vas"ō-pres'in),[key] —n. 1. Biochem.a peptide hormone, synthesized in the hypothalamus and released by the posterior pituitary gland, that stimulates capillary muscles and reduces the flow of urine and increases its concentration.
2. Pharm.a synthetic preparation of this hormone, used as an antidiuretic in the treatment of diabetes insipidus. Also called antidiuretic hormone, ADH.