/ Dictionary / Index G gentamicin: Meaning and Definition of Find definitions for: gen•ta•mi•cin Pronunciation: ( jen"tu-mī'sin), [key] — n. Pharm. a highly toxic broad-spectrum antibiotic mixture of related aminoglycoside substances derived from the actinomycete bacterium Micromonospora purpurea, used in its sulfate form in the treatment of severe Gram-negative infections. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: gentamicin (Thesaurus) gent genteel Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language