/ Dictionary / Index H hexamethonium: Meaning and Definition of Find definitions for: hex•a•me•tho•ni•um Pronunciation: (hek"su-mu-thō'nē-um), [key] — n. Pharm. a compound, CHN, used in the treatment of severe hypertension to lower blood pressure and increase blood flow by blocking transmission of nerve impulses that constrict blood vessels. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. hexameter hexamethylene Related Content Daily Word Quiz: supine Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language