/ Dictionary / Index C clonidine: Meaning and Definition of Find definitions for: clon•i•dine Pronunciation: (klon'i-dēn", klō'ni-), [key] — n. Pharm. a synthetic white crystalline substance, CHClN, used in the treatment of high blood pressure. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: clonidine (Thesaurus) clonic spasm cloning Related Content Daily Word Quiz: lyre Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language