# influenza

/ˌɪnfɫuˈɛnzə/ (US) · /ˌɪnfluːˈɛnzɐ/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/influenza
Updated: 2026-05-06

## Definition

a common illness that causes a fever, body aches, and a cough. It is more serious than a cold and is often called the flu.

For teachers: an acute, highly contagious viral infection of the respiratory tract, typically characterised by inflammation of the mucous membranes, fever, and muscular pain.

## Examples

- He stayed home from work because he had influenza.
- Health officials recommend getting a vaccine every year to protect against the most common strains of influenza.
- The 1918 influenza pandemic remains one of the deadliest events in human history, illustrating how rapidly a respiratory virus can spread across a globally connected population.

## Pitfalls

- Not "I have a influenza" but "I have influenza" — When using the full medical term, it is treated as an uncountable mass noun and does not take an indefinite article.

## Usage notes

- Often used with the definite article ('the flu') in common speech; 'influenza' is preferred in medical or formal contexts.

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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.