/ Dictionary / Index P prolactin: Meaning and Definition of Find definitions for: pro•lac•tin Pronunciation: (prō-lak'tin), [key] — n. Biochem. an anterior pituitary polypeptide hormone that stimulates lactation by the mammary glands at parturition in mammals, the activity of the crop in birds, and in some mammalian species the production of progesterone by the corpus luteum. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: prolactin (Thesaurus) Prokopyevsk prolamin Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language