/ Dictionary / Index A actinomycin: Meaning and Definition of Find definitions for: ac•tin•o•my•cin Pronunciation: (ak-tin"ō-mī'sin, ak"tu-nō-), [key] — n. Pharm. any of a group of related antibiotics derived from several species of streptomyces bacteria, used against susceptible bacteria and fungi and in the treatment of various cancers. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: actinomycin (Thesaurus) actinomycete actinomycin D Related Content Daily Word Quiz: hedonist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language