infect
Americanverb (used with object)
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infects,
present (3rd person singular)
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infected,
past participle, past
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infecting
present participle
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to affect or contaminate (a person, organ, wound, etc.) with disease-producing germs.
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to affect with disease.
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to taint or contaminate with something that affects quality, character, or condition unfavorably.
to infect the air with poison gas.
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to corrupt or affect morally.
The news of the gold strike infected him with greed.
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to imbue with some pernicious belief, opinion, etc.
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to affect with a computer virus.
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to affect so as to influence feeling or action.
His courage infected the others.
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Law. to taint with illegality, or expose to penalty, forfeiture, etc.
verb (used without object)
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infects,
present (3rd person singular)
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infected,
past participle, past
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infecting
present participle
adjective
verb
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to cause infection in; contaminate (an organism, wound, etc) with pathogenic microorganisms
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(also intr) to affect or become affected with a communicable disease
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to taint, pollute, or contaminate
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to affect, esp adversely, as if by contagion
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computing to affect with a computer virus
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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
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infectednessnoun
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infecternoun
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infectornoun
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preinfectverb (used with object)
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reinfectverb (used with object)
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infectantadjective
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noninfectedadjective
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noninfectingadjective
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uninfectedadjective
Inflected Forms
Participles
Conjugated Forms
Present
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infectsimple
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infectssimple
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have infectedperfect
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has infectedperfect
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am infectingprogressive
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are infectingprogressive
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is infectingprogressive
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have been infectingperfect progressive
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has been infectingperfect progressive
Past
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infectedsimple
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had infectedperfect
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was infectingprogressive
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were infectingprogressive
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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:
Gen. Rob Bonta’s office, arguing “persistent and pervasive racial disparities infect California’s death penalty system.”
From Los Angeles Times ● Nov. 5, 2026
These are viruses that naturally infect bacteria and can destroy them.
From Science Daily ● Nov. 5, 2026
Although viruses depend entirely on the cells they infect to supply energy and manufacture proteins, producing excessive amounts of viral RNA can damage the very machinery they need to reproduce.
From Science Daily ● Oct. 21, 2026
He goes on to emphasize that what Claude found — a previously uncharacterized enzyme system found in viruses that infect bacteria — isn’t necessarily going to be useful.
From Salon ● Sep. 30, 2026
The virus, therefore, could infect the lungs on contact.
From "The Hot Zone" by Richard Preston
It’s caused by a bacteria called Yersinia pestis that infects fleas and the small mammals that host fleas, and there are actually three types of plague depending on which part of the body becomes infected.
From Slate ● Oct. 8, 2026
The other forms of plague are bubonic, which infects the lymph nodes, and septicemic, which is transmitted in the bloodstream and is also very deadly.
From The Wall Street Journal ● Oct. 6, 2026
Rabies infects very few humans in the United States and California, according to the state public health department.
From Los Angeles Times ● Oct. 1, 2026
The virus that sparked a global pandemic still regularly infects, disables and kills hundreds of people per week.
From Salon ● Aug. 6, 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
One important way of stopping Ebola from spreading is contact tracing - finding all those people who had come into contact with an infected person and putting them into isolation.
From BBC ● Nov. 12, 2026
More than 5,400 people have died and 11,000 infected with Ebola in DR Congo since the outbreak was declared in May.
From BBC ● Nov. 12, 2026
These findings indicate that infected animals had supplied some of the skins used to produce the documents.
From Science Daily ● Nov. 11, 2026
Those infected during infancy are particularly likely to develop chronic infections, which kill up to 25% of people, mostly through liver failure or liver cancer, according to data published in 2020.
From BBC ● Nov. 5, 2026
It bled and hurt, but my other ailments were already causing me so much trouble that I let this one slide, which was stupid of me, because now I’m walking around with an infected toe.
From "The Diary of a Young Girl" by Anne Frank
Although this sacrifice kills the individual cell, it prevents the virus from producing more copies and infecting nearby bacteria, helping protect the larger colony.
From Science Daily ● Oct. 31, 2026
Sealing off: Leronlimab blocks what's left of the virus from infecting immune cells -- the equivalent of sealing off the room with a water-tight valve.
From Science Daily ● Aug. 13, 2026
Around 3 a.m. one night, they observed one of their viruses successfully replicating, and infecting and killing bacterial cells.
From The Wall Street Journal ● Aug. 7, 2026
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
Yellow fever was wrestling the life out of Philadelphia, infecting the cobblestones, the trees, the nature of the people.
From "Fever 1793" by Laurie Halse Anderson
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