/ Dictionary / Index T tobramycin: Meaning and Definition of Find definitions for: to•bra•my•cin Pronunciation: (tō"bru-mī'sin), [key] — n. Pharm. a highly toxic aminoglycoside antibiotic, CHNO, derived from Streptomyces tenebarius, used in the treatment of serious infections due to susceptible Gram-positive and Gram-negative organisms. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: tobramycin (Thesaurus) Tobolsk toby Related Content Daily Word Quiz: careening Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language