1) Antibiotic 2) Antibiotic drug 
Carbomycin, also known as magnamycin, is a colorless, optically active crystalline macrolide antibiotic with the molecular formula C42H67NO16. It is derived from the bacterium Streptomyces halstedii and active in inhibiting the growth of Gram-positive bacteria and `certain Mycoplasma strains.` Its structure was first proposed by Robert Woodward .....
A macrolide antibiotic isolated from Streptomyces halstedii; similar to erythromycin and used as an antibacterial and antimicrobial. ... (05 Mar 2000) ... 
[n] - a colorless basic antibiotic that inhibits the growth of Gram-positive organisms
noun a colorless basic antibiotic that inhibits the growth of Gram-positive organisms