/ Dictionary / Index H hydralazine: Meaning and Definition of Find definitions for: hy•dral•a•zine Pronunciation: (hī-dral'u-zēn"), [key] — n. Pharm. a white crystalline powder, CHN, that dilates blood vessels and is used in the treatment of hypertension. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: hydralazine (Thesaurus) hydra-headed hydrangea Related Content Daily Word Quiz: pundit Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language