# delirium

/dɪˈɫɪɹiəm/ (US) · /dɪlˈɪɹiəm/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/delirium
Updated: 2026-05-18

## Definition

a state of being very confused and having strange thoughts, often because of a high fever or a serious illness. You might feel like you are seeing things that are not there.

For teachers: a state of mental confusion characterized by incoherent speech and hallucinations, typically resulting from a high fever or severe illness. Often used to describe a temporary loss of mental clarity.

## Examples

- The patient suffered from delirium after the surgery.
- Doctors monitored the patient closely for signs of delirium, as high fevers can cause severe confusion in the elderly.
- The sudden onset of delirium often signals a systemic infection or metabolic imbalance, requiring immediate intervention to prevent further neurological damage.

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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.