# virus

/ˈvaɪɹəs/ (US) · /vˈaɪɹəs/ (UK)

Source: https://englishreference.com/word/virus
Updated: 2026-06-19

## Senses

### 1. biological germ

noun · CEFR A2

a tiny living thing that enters your body and can make you sick.

For teachers: a submicroscopic infectious agent that replicates only inside the living cells of an organism.

- The doctor said my sore throat was caused by a common virus.
- Researchers are studying how the virus mutates when it moves from animal hosts to human populations.

### 2. illness

noun · CEFR B1 · Informal

a sickness or infection caused by a virus.

For teachers: an illness or medical condition resulting from a viral infection.

- I missed three days of work because of a stomach virus.
- The school reported a high number of absences this week due to a seasonal respiratory virus circulating among the students.

### 3. malicious software

noun · CEFR B1

a harmful computer program that can copy itself and damage your files.

For teachers: a piece of code which is capable of copying itself and typically has a detrimental effect, such as corrupting the system or destroying data.

- Never click on suspicious links or you might get a virus on your laptop.
- The company's security software detected a sophisticated virus that was attempting to encrypt sensitive financial records.

### 4. harmful influence

noun · CEFR C1 · Literary

something bad or dangerous that spreads quickly from person to person.

For teachers: a harmful or corrupting influence that spreads rapidly within a group or society.

- Hatred can spread like a virus through a community.
- The orator warned that misinformation was a virus threatening the very foundations of their democratic institutions.

## Examples

- Wash your hands so you do not catch a virus.
- The school closed for two days because a stomach virus was spreading quickly among the students and staff.
- Because antibiotics target bacteria, they are completely ineffective against a virus, forcing doctors to rely on vaccines, antiviral medications, or the patient's own immune system.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.