infect

infect — verb

1. to make a living thing ill by giving it a germ, virus, or other microbe that cau

1.verbtransitiveB1
Definition

to make a living thing ill by giving it a germ, virus, or other microbe that causes disease

Example

The flu virus infected nearly thirty students at Mizuki's school within a week.

infect + person/group with + disease

Doctors warned travellers that mosquitoes infected with the virus could spread it quickly.

passive: infected with + disease

Common collocations
  • infect someone with a disease
  • become infected with
  • get infected
  • infected patient / person / animal
Synonyms
  • contaminate

    Broader — can mean any harmful substance (chemical, radiation), not just living germs

  • transmit

    Focuses on the act of passing the disease, not on the result of becoming sick; often followed by 'to'.

  • spread

    Can be transitive or intransitive; less clinical and used for both diseases and rumours

  • pass on

    Informal phrasal verb — 'pass on a cold to someone'

Antonyms
  • protect

    To keep someone safe from disease (often used with 'from')

  • vaccinate

    To give someone a vaccine to prevent infection

Grammar Patterns

infect + person/animal/plant

be infected with + disease

Usage Note

Often used in the passive form (be/get infected). Most commonly describes person-to-person or animal-to-person transmission through air, touch, or insects.

Common Mistakes

The virus infected to me.
The virus infected me.
'infect' is transitive; do not add 'to' after it.
I infected a cold.
I caught a cold.' or 'I was infected with a cold.
'infect' describes the action of the germ or the person who passes the disease, not the person who becomes sick.
The food infected me with bacteria.
The food was infected with bacteria.
For objects/food, the passive form is more natural.

2. to contain harmful bacteria or germs that can cause illness, usually describing

2.verbtransitiveB2
Definition

to contain harmful bacteria or germs that can cause illness, usually describing a wound, cut, body part, food, or water supply that has been contaminated

Example

The nurse cleaned Élise's cut carefully to make sure it did not become infected.

often passive: become infected

Bacteria from dirty water can infect an open wound very quickly if left untreated.

infect + wound

Common collocations
  • infected wound / cut / finger
  • become infected
  • get infected
  • infected with bacteria / germs
Synonyms
  • contaminate

    Broader — can refer to chemicals, radiation, or dirt, not just bacteria

  • fester

    Describes the rotting result of an infected wound, not the act of infection

Antonyms
  • disinfect

    To clean something to remove harmful germs

  • sterilize

    To make something completely free of all microorganisms

Grammar Patterns

be infected (with/by + bacteria/germs)

infect + wound / cut / object

Usage Note

This sense is very frequently passive (become/get infected). The subject is typically a wound, body part, food item, or water source — not a person directly. Distinguish from sense 1 (SPREAD DISEASE), where the subject is a disease or a sick organism passing illness to another.

Common Mistakes

The wound infected.
The wound became infected.' or 'Bacteria infected the wound.
'infect' is transitive; a wound cannot 'infect' itself.

3. to make a feeling, mood, or attitude spread from one person to another — for exa

3.verbtransitiveB2
Definition

to make a feeling, mood, or attitude spread from one person to another — for example, a speaker's excitement infecting the audience, or a friend's optimism infecting those around them

Example

The young teacher's passion for science infected her students, and several joined the science club.

infect + group + with + emotion

Valentina's laughter was so joyful that it infected everyone in the hospital waiting room.

emotion infects people

Common collocations
  • infect someone with enthusiasm / excitement / optimism
  • infect a group / crowd / team
  • be infected by someone's mood
Synonyms
  • spread to

    More neutral; 'infect' suggests stronger, more irresistible emotional transfer

  • rub off on

    Informal phrasal verb — 'Her energy rubbed off on everyone.'

  • influence

    Broader and less vivid; does not carry the idea of quick, involuntary spread

Antonyms
  • dampen

    To make a feeling weaker — 'The bad news dampened everyone's excitement.'

  • contain

    To keep a feeling from spreading — 'She tried to contain her panic.'

Grammar Patterns

infect + person/group + with + emotion

emotion/mood + infects + person/group

Usage Note

Frequently used with positive emotions (enthusiasm, excitement, joy, optimism, passion, laughter). The subject is usually an emotion, a person's quality, or an atmosphere. Unlike senses 1-2, there is no literal biological contamination.

Common Mistakes

Her sadness infected to him.
Her sadness infected him.
No preposition 'to' after 'infect'.
The party was infected with music.
The party was filled with music.
'infect' in this sense is for feelings/emotions, not physical things like music or decorations.

4. to cause a computer, program, or file to be damaged or controlled by a malicious

4.verbtransitiveB2
Definition

to cause a computer, program, or file to be damaged or controlled by a malicious program or virus that copies itself

Example

A computer virus infected the company's main server and destroyed thousands of customer records.

infect + computer system

Yan's laptop was infected by a program that stole his passwords and bank details.

passive: be infected by + malware

Common collocations
  • infect a computer / device / network / server
  • be infected with a virus / malware / spyware
  • infected file / program
Synonyms
  • compromise

    Broader computing term — includes hacking, unauthorized access, not just malware

  • corrupt

    Focuses on the result (damaged files) rather than the act of infecting

Antonyms
  • protect

    To keep a computer safe from viruses and malware

  • clean

    To remove a virus or malware from an infected system

Grammar Patterns

infect + computer / system / network / files

be infected with/by + virus / malware

Usage Note

In computing contexts, 'infect' always implies a harmful program (virus, worm, trojan, spyware, ransomware). In everyday conversation, Taiwanese users often say '電腦中毒了' (the computer is poisoned) instead of 'the computer was infected.'

Common Mistakes

A virus infected to my computer.
A virus infected my computer.
No preposition 'to' after 'infect'.
My phone infected a virus.
My phone was infected with a virus.
The phone receives the infection; use the passive form.

Word family

Synonym discussion

Sense: verb/1

All five words describe moving something harmful from one place to another, but they differ in scope and register. 'Infect' (sense 1) specifically involves living germs, viruses, or pathogens that cause disease in a living organism — it implies the germ enters and multiplies inside the host. 'Contaminate' is broader: it can refer to chemicals, radiation, dirt, or bacteria making something impure or unsafe, without the germ multiplying inside a host (e.g., 'contaminated water'). 'Transmit' is clinical and focuses on the mechanism of passing a disease (e.g., 'mosquitoes transmit malaria'); it does not say whether the receiver actually becomes sick. 'Spread' is the most general and can be used for diseases, rumours, or news; it works as both transitive and intransitive ('the disease spread quickly'). 'Pass on' is an informal phrasal verb commonly used for minor illnesses like colds and flu ('She passed her cold on to me'). For everyday talk about catching a cold, use 'pass on' or 'spread'; in medical writing, use 'transmit' or 'infect'; for non-living contamination, use 'contaminate'.

infect ↗contaminate ↗transmit ↗spread ↗pass on ↗

Common collocations

Nouns

Adverbs

Phrases

  • infect with
  • become infected
  • get infected
  • be infected by

Prepositions

Etymology

LatinFrenchEnglish

'Infect' entered English in the 14th century from Latin 'inficere' (to put in, dip into, stain, corrupt), formed from 'in-' (in) and 'facere' (to make, do). The original meaning was 'to stain or dye' something; the medical sense of 'passing disease' emerged in the 1300s, drawing on the idea of something being stained or tainted by illness. The figurative meaning (emotions spreading) appeared in the 1600s, and the computing sense (viruses spreading between computers) was first recorded in the 1970s alongside the rise of computer viruses.