Word
delusional
Phoneticsdelu·sion·al
US/dɪˈɫuʒənəɫ/
UK/dɪlˈuːʒənəl/
Definitions
01having false beliefs
B2 · Upper Intermediate
adj. believing something that is not true, even when there is proof that you are wrong.
adj. 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.”
Synonyms
02relating to a medical delusion
C1 · Advanced Medicine Technical
adj. relating to a serious mental health condition where a person cannot tell what is real.
adj. 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.”
Synonyms
03a person with delusions
C2 · Proficiency Countable noun Formal
n. a person who believes things that are not true.
n. 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.
Real-World Examples
“This may be delusional, but I don’t believe the work done in the last third of my life is inferior to that done near its beginning.” “He is among a group of researchers studying how chatbots respond to delusional thinking to try to identify who might be most at risk.” Etymology
From delusion + -al.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
NOUN
ADJECTIVE
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B2 FirstIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.5.5–6.5TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 4.0–4.572–94TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.785–944
- Frequency
- Frequent
- Level
- B2 · Upper Intermediate
- Updated
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