penicillin
any of a group of antibiotics with powerful bactericidal action, used to treat many types of infections, including pneumonia, gonorrhoea, and infections caused by streptococci and staphylococci: originally obtained from the fungus Penicillium, esp P. notatum. Formula: R-C9H11N2O4S where R is one of several side chains
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
penicillin
[‚pen·ə′sil·ən] (microbiology)
The collective name for salts of a series of antibiotic organic acids produced by a number of Penicillium and Aspergillus species; active against most gram-positive bacteria and some gram-negative cocci.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.