penicillin

[pen-uh-sil-in]
noun Pharmacology.
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.

Origin:
1925–30; penicill(ium) + -in2

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World English Dictionary
penicillin (ˌpɛnɪˈsɪlɪn)
 
n
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
 
[C20: from penicillium]

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Etymonline
Word Origin & History

penicillin
1929, coined in Eng. by Alexander Fleming (1881-1955), who first recognized its antibiotic properties, from Mod.L. Penicillium notatum (1867), the name of the mould from which it was first obtained, from L. penicillus "paintbrush" (see pencil), in reference to the shape of the mould cells.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

penicillin pen·i·cil·lin (pěn'ĭ-sĭl'ĭn)
n.
Any of a group of broad-spectrum antibiotic drugs obtained from penicillium molds or produced synthetically, most active against gram-positive bacteria and used in the treatment of various infections and diseases.

The American Heritage® Stedman's Medical Dictionary
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American Heritage
Science Dictionary
penicillin   (pěn'ĭ-sĭl'ĭn)  Pronunciation Key 
An antibiotic drug obtained from molds of the genus Penicillium and used to treat or prevent various infections caused by gram-positive bacteria such as streptococcus. Penicillin was the first of a class of antibiotics (whose names end in -icillin) that are derived from it and are active against a broader spectrum of bacteria. See Note at Alexander Fleming.
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Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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American Heritage
Cultural Dictionary

penicillin definition


An antibiotic that is used to treat infections caused by some kinds of bacteria. Penicillin, which is derived from a common kind of mold that grows on bread and fruit, was the first antibiotic discovered and put into widespread use.

Note: Penicillin was first widely used during World War II.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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Example sentences
And you are right that they lack the critical training to tell penicillin from
  snake oil.
Penicillin is so good at killing bacteria that bacteria have had to evolve a
  way around it.
He chose one that he thought, at this point, would be even more effective than
  penicillin.
Even bacteria completely immune to penicillin and its cousins could be killed.
Images for penicillin
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