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[in-fekt] /ɪnˈfɛkt/
verb (used with object)
to affect or contaminate (a person, organ, wound, etc.) with disease-producing germs.
to affect with disease.
to taint or contaminate with something that affects quality, character, or condition unfavorably:
to infect the air with poison gas.
to corrupt or affect morally:
The news of the gold strike infected him with greed.
to imbue with some pernicious belief, opinion, etc.
to affect with a computer virus.
to affect so as to influence feeling or action:
His courage infected the others.
Law. to taint with illegality, or expose to penalty, forfeiture, etc.
verb (used without object)
to become infected.
Archaic. infected.
Origin of infect
1350-1400; Middle English infecten < Latin infectus (past participle of inficere to immerse in dye, discolor, taint, poison), equivalent to in- in-2 + -fec-, combining form of facere to do1, make (see fact) + -tus past participle suffix
Related forms
infectant, adjective
infectedness, noun
infector, infecter, noun
noninfected, adjective
noninfecting, adjective
preinfect, verb (used with object)
reinfect, verb (used with object)
uninfected, adjective
Can be confused
afflict, infect, inflict.
infect, infest, invest.
5. damage, corrupt. 6. touch, stir, arouse. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for infect
Contemporary Examples
Historical Examples
  • There must be some sort of bacteria in fish which infect the catcher and impel him to expand facts whether he will or not.

    Through Arctic Lapland Cutcliffe Hyne
  • Stand clear of rashness, and have nothing of insincerity or self-love to infect you.

    Dickory Cronke Daniel Defoe
  • Such a patient then would not be as likely to infect a mosquito as would one less seriously affected.

    Insects and Diseases Rennie W. Doane
  • He may kiss any member of his family, or a baby, and infect them.

  • The Garrison made sure that no dangerous bacteria, fungus, or what-not arrived to infect the system.

    Piper in the Woods Philip K. Dick
British Dictionary definitions for infect


verb (mainly transitive)
to cause infection in; contaminate (an organism, wound, etc) with pathogenic microorganisms
(also intransitive) to affect or become affected with a communicable disease
to taint, pollute, or contaminate
to affect, esp adversely, as if by contagion
(computing) to affect with a computer virus
(mainly international law) to taint with crime or illegality; expose to penalty or subject to forfeiture
(archaic) contaminated or polluted with or as if with a disease; infected
Derived Forms
infector, infecter, noun
Word Origin
C14: from Latin inficere to dip into, stain, from facere to make
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for infect

late 14c., from Latin infectus, past participle of inficere "to spoil, stain," literally "to put in to, dip into," from in- "in" (see in- (2)) + facere "perform" (see factitious). Related: Infected; infecting.

Online Etymology Dictionary, © 2010 Douglas Harper
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infect in Medicine

infect in·fect (ĭn-fěkt')
v. in·fect·ed, in·fect·ing, in·fects

  1. To contaminate with a pathogenic microorganism or agent.

  2. To communicate a pathogen or disease to another organism.

  3. To invade and produce infection in an organ or body part.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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