infect

American  

[in-fekt] / ɪnˈfɛkt /

verb (used with object)

1. to affect or contaminate (a person, organ, wound, etc.) with disease-producing germs.

2. to affect with disease.

3. to taint or contaminate with something that affects quality, character, or condition unfavorably.

   to infect the air with poison gas.

4. to corrupt or affect morally.

   The news of the gold strike infected him with greed.

5. to imbue with some pernicious belief, opinion, etc.

   Synonyms:

   corrupt, damage

6. to affect with a computer virus.

   Synonyms:

   arouse, stir, touch

7. to affect so as to influence feeling or action.

   His courage infected the others.

8. Law. to taint with illegality, or expose to penalty, forfeiture, etc.

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verb (used without object)

1. to become infected.

adjective

1. Archaic. infected.

infect British  

/ ɪnˈfɛkt /

verb

1. to cause infection in; contaminate (an organism, wound, etc) with pathogenic microorganisms

2. (also intr) to affect or become affected with a communicable disease

3. to taint, pollute, or contaminate

4. to affect, esp adversely, as if by contagion

5. computing to affect with a computer virus

6. international law to taint with crime or illegality; expose to penalty or subject to forfeiture

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adjective

1. archaic contaminated or polluted with or as if with a disease; infected

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

• infectant adjective
• infectedness noun
• infecter noun
• infector noun
• noninfected adjective
• noninfecting adjective
• preinfect verb (used with object)
• reinfect verb (used with object)
• uninfected adjective

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 ( fact ) + -tus past participle suffix

Example Sentences

The law doesn’t allow ulterior motives to infect plan investments.

From The Wall Street Journal • Mar. 30, 2026

Once inside a tumor cell, the virus destroys it and then produces copies of itself that move on to infect neighboring cancer cells.

From Science Daily • Mar. 20, 2026

The virus is so contagious that any misstep could kill the patient on board and infect the crew members, who would then be vectors to spread the deadly pathogens across America.

From The Wall Street Journal • Mar. 20, 2026

South Koreans hailed their latest cultural product to infect the world with "K-syndrome" -- the irresistible surrender to the country's movies, music, books, fashion and cuisine.

From Barron's • Mar. 16, 2026

If it didn’t work, the virus would infect the cells, causing damage scientists could see using a microscope.

From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot

Related Words

• affect
• poison
• taint
• touch