| Noun | 1. | erythromycin - an antibiotic (trade name Erythrocin or E-Mycin or Ethril or Ilosone or Pediamycin) obtained from the actinomycete Streptomyces erythreus; effective against many Gram-positive bacteria and some Gram-negativeantibiotic, antibiotic drug - a chemical substance derivable from a mold or bacterium that kills microorganisms and cures infections; "when antibiotics were first discovered they were called wonder drugs" | |