vancomycinEnglishOxford New American Dictionaryvancomycin /ˌvaNGkəˈmīsin, , ˌvæŋkəˈmaɪsɪn , ˌvaNGkəˈmīsn, ˌvæŋkəˈmaɪsn/ ▸ noun Medicine a bacterial antibiotic used against resistant strains of streptococcus and staphylococcus. This antibiotic is obtained from the bacterium Streptomyces orientalis. – ORIGIN 1950s : from vanco- (of unknown origin) + -mycin.