penicillin: Meaning and Definition of
Pronunciation: (pen"u-sil'in), [key]
— n. Pharm.
- any of several antibiotics of low toxicity, produced naturally by molds of the genus Penicillium and also semisynthetically, having a bactericidal action on many susceptible Gram-positive or Gram-negative cocci and bacilli, some also being effective against certain spirochetes.
- penicillin (Thesaurus)