/ Dictionary / Index R relaxin: Meaning and Definition of Find definitions for: re•lax•in Pronunciation: (ri-lak'sin), [key] — n. Biochem., Pharm. a polypeptide hormone produced by the corpus luteum during pregnancy that causes the pelvic ligaments and cervix to relax during pregnancy and delivery. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: relaxin (Thesaurus) relaxed re-lay Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language