# pneumonia

/nəˈmoʊnjə/ (US) · /njuːmˈəʊniə/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/pneumonia
Updated: 2026-05-02

## Definition

a serious illness that affects your lungs and makes it hard to breathe. It is usually caused by an infection from bacteria or a virus.

For teachers: an inflammatory condition of the lung affecting primarily the microscopic air sacs known as alveoli. Typically caused by infection with viruses or bacteria and less commonly by other microorganisms, certain drugs, or autoimmune diseases.

## Examples

- He spent a week in the hospital recovering from pneumonia.
- The doctor prescribed a course of antibiotics to treat the bacterial pneumonia and clear the patient's lungs.
- While modern medicine has significantly reduced the mortality rate, pneumonia remains a leading cause of death among the elderly and those with compromised immune systems worldwide.

## Usage notes

- Uncountable when referring to the disease in general; countable when referring to a specific case or instance of the illness.

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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.