/ Dictionary / Index D demeclocycline: Meaning and Definition of Find definitions for: dem•e•clo•cy•cline Pronunciation: (dem"u-klō-sī'klēn), [key] — n. Pharm. a broad-spectrum antibiotic, CHClNO, derived from a mutant strain of the bacterium Streptomyces aureofaciens: used against a wide range of susceptible microorganisms. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. demeanor dement Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language