infect
Americanverb (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)
adjective
verb
-
to cause infection in; contaminate (an organism, wound, etc) with pathogenic microorganisms
-
(also intr) 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
-
international law to taint with crime or illegality; expose to penalty or subject to forfeiture
adjective
Usage
What does infect mean? Infect is a verb that means to taint someone or something with disease-causing germs or to spread a disease to another living thing, as in The doorknob was infected with disease-causing bacteria. Infect can also mean to taint something in a way that negatively affects quality, as in The water was infected with toxic chemicals. Computers and other devices that connect to the internet can also become infected. Instead of a virus of living organisms infecting your computer, though, bits of code attack your computer system to do harm. Infect is also used figuratively to mean to corrupt something in various ways. It can mean something was corrupted morally, as in The constant flattery caused him to be infected with hubris. Infect can also be used to mean someone has been corrupted by harmful thoughts or beliefs, as in He allowed hatred to infect his mind. The adjective infectious is used to mean something is capable of infecting things, as in Doctors worked to stop the spread of the infectious disease. Infect can be confused with infest, which means to overrun a place or live there in an unwanted manner. Example: Tia stayed home from school so she wouldn’t infect her classmates with the flu.
Other Word Forms
Derived Forms
-
infectednessnoun
-
infecternoun
-
infectornoun
-
preinfectverb (used with object)
-
reinfectverb (used with object)
-
infectantadjective
-
noninfectedadjective
-
noninfectingadjective
-
uninfectedadjective
Inflected Forms
Participles
Conjugated Forms
Present
-
infectsimple
-
infectssimple
-
have infectedperfect
-
has infectedperfect
-
am infectingprogressive
-
are infectingprogressive
-
is infectingprogressive
-
have been infectingperfect progressive
-
has been infectingperfect progressive
Past
-
infectedsimple
-
had infectedperfect
-
was infectingprogressive
-
were infectingprogressive
-
had been infectingperfect progressive
Future
Etymology
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 do 1, make ( see fact) + -tus past participle suffix
Explanation
To infect is to spread an illness to another person. If you sneeze on your friend, you may inadvertently infect her with your germs. When a disease moves from person to person, it infects them. Most diseases only spread within one species, although there are some, like avian flu, that can infect both humans and other animals. Another way to infect someone is to deeply affect them with an idea or emotion: "His enthusiasm for music infects the class with excitement." The Latin root, inficere, means "to spoil or stain" and "to dip into."
Vocabulary lists containing infect
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
The issue is further complicated by bacteriophages, which are viruses that infect bacteria.
From Science Daily ● Jul. 17, 2026
Unlike a virus, the parasite can’t spread directly from animal to animal, and it requires an open wound to infect an animal, Talbot said.
From MarketWatch ● Jun. 10, 2026
Bacteria can also infect wounds where screwworm maggots are present and may cause an infection that can lead to symptoms like fever or chills.
From Los Angeles Times ● Jun. 6, 2026
Ebola viruses normally infect animals, but outbreaks among humans can sometimes start when people eat or handle infected animals.
From BBC ● May 24, 2026
The unknown agent could infect monkey cells and pop them.
From "The Hot Zone" by Richard Preston
The U.K. also announced sanctions against hackers responsible for Lumma Stealer, malware that sucks up sensitive information from devices it infects.
From The Wall Street Journal ● Jul. 13, 2026
The virus normally infects animals, typically fruit bats, but outbreaks among humans can sometimes start when people eat or handle infected animals.
From BBC ● Jun. 30, 2026
The species, named Taczanowskia waska, represents the first known example of a spider mimicking the appearance of a fungus that infects spiders.
From Science Daily ● Jun. 17, 2026
The contagion is typically found in rodents and rarely infects humans.
From The Wall Street Journal ● May 7, 2026
Engineered pollen blows just as easily as the original kind and infects all traditional plants in its path.
From "The Adoration of Jenna Fox" by Mary E. Pearson
Michigan has been the hardest hit state, with health officials there saying on Friday that the number infected has increased to more than 8,100.
From BBC ● Jul. 24, 2026
To model realistic transmission conditions, the researchers created a controlled system in which infected and uninfected animals either came into direct physical contact or shared the same airspace without touching.
From Science Daily ● Jul. 24, 2026
According to state figures, external, 286 people there have been infected by cyclosporiasis - which comes from ingesting the cyclospora parasite, and includes symptoms like "explosive diarrhoea".
From BBC ● Jul. 24, 2026
Another infectious traveler passed through LAX while infected with measles earlier this month.
From Los Angeles Times ● Jul. 23, 2026
“What! No! Heavens! I scarcely survive traipsing through the slums, only to find my own house infected with plague! Eek! Eek!”
From "The Hidden Gallery" by Maryrose Wood
In an interview with the Reuters news agency, Gaston urged the child and her mother to go to a health centre, as they risked "worsening their health" and "infecting their relatives".
From BBC ● Jun. 17, 2026
Even with this early identification, the outbreak spiraled into the deadliest Ebola epidemic in history, infecting over 28,000 and killing over 11,000.
From The Wall Street Journal ● May 22, 2026
With hantavirus, the incubation period can take up to six weeks, so people must be isolated for a really long time to ensure they won’t get sick and start infecting others.
From Slate ● May 16, 2026
But some do end up being “superspreaders,” infecting others at exceptional rates.
From Los Angeles Times ● May 14, 2026
Now, after a gap of 37 years, the fever was back again, infecting and killing more and more people every day.
From "An American Plague: The True and Terrifying Story of the Yellow Fever Epidemic of 1793" by Jim Murphy
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
