# delusional

/dɪˈɫuʒənəɫ/ (US) · /dɪlˈuːʒənəl/ (UK)

Source: https://englishreference.com/word/delusional
Updated: 2026-06-20

## Senses

### 1. having false beliefs

adjective · CEFR B2

believing something that is not true, even when there is proof that you are wrong.

For teachers: holding idiosyncratic beliefs that are maintained despite being contradicted by reality or rational argument.

- He was delusional if he thought he could finish the whole project in one day.
- The CEO's delusional insistence that the company was profitable led to a complete lack of preparation for the upcoming audit.

### 2. relating to a medical delusion

adjective · CEFR C1 · Technical

relating to a serious mental health condition where a person cannot tell what is real.

For teachers: pertaining to or characterised by clinical delusions as a symptom of a psychiatric disorder.

- The patient was experiencing delusional thoughts and needed professional help.
- The psychiatrist noted that the patient's delusional episodes were becoming more frequent and less responsive to the current medication dosage.

### 3. a person with delusions

noun · CEFR C2 · Formal

a person who believes things that are not true.

For teachers: an individual suffering from a delusion or a delusional disorder.

- The book describes the tragic life of a delusional who believed he was a king.
- In his early essays, the philosopher treats the delusional not as a patient to be cured, but as a subject with a unique perspective on reality.

Usage: This noun use is relatively rare and can sound clinical or insensitive; the adjective is much more common.

## Examples

- He is delusional about his chances of winning.
- The manager remained delusional about the project's success despite mounting losses and staff complaints.
- Critics argued that the politician's delusional view of public opinion blinded him to the growing unrest in the streets.

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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.