delusion
C1Formal, Academic, Medical, Everyday (in metaphorical use)
Definition
Meaning
A persistent false belief held in the face of strong contradictory evidence, especially as a symptom of mental disorder.
A mistaken or misleading belief, idea, or impression that is not based on reality, held by an individual or group.
Linguistics
Semantic Notes
In clinical/psychiatric contexts, a 'delusion' is a fixed, false belief resistant to reason. In everyday use, it refers to a serious self-deception or collective misconception, often with a negative connotation of being dangerously out of touch with reality.
Dialectal Variation
British vs American Usage
Differences
No significant difference in core meaning or usage. Spelling is identical.
Connotations
Identical connotations in both varieties.
Frequency
Slightly more frequent in American English in the Corpus of Contemporary American English (COCA) vs. the British National Corpus (BNC), but the difference is marginal.
Vocabulary
Collocations
Grammar
Valency Patterns
delusion that + clausedelusion about + noun/gerunddelusion of + noun (e.g., grandeur)under the delusion that + clauseVocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “labour under a delusion/delusions”
- “free from delusion”
Usage
Context Usage
Business
Used to describe a strategic plan or market belief that is fundamentally flawed and disconnected from real conditions (e.g., 'The board was operating under the delusion of infinite growth.').
Academic
Common in psychology, psychiatry, philosophy, and critical theory to denote fixed false beliefs, either clinical or ideological.
Everyday
Used to accuse someone of being severely mistaken or self-deceived (e.g., 'You're under the delusion that I'll agree to that.').
Technical
In clinical psychology/psychiatry, a specific symptom of disorders like schizophrenia, defined by diagnostic criteria (DSM-5/ICD-11).
Examples
By CEFR Level
- He had the silly delusion that he could fly.
- It is a delusion to think money brings happiness.
- She was under the delusion that her boss was going to promote her.
- The politician's speech was based on a popular delusion about easy solutions.
- The cult leader exploited the shared delusion of his followers for his own gain.
- Modern psychiatry aims to treat the delusions associated with severe mental illness without stigma.
- The author argues that the national ethos was built upon a foundational delusion regarding its colonial history.
- His grandiose delusions of being a secret royal heir led to a complete breakdown in his social functioning.
Learning
Memory Aids
Mnemonic
Think: 'DE-LUSION' sounds like 'the illusion' but starts with 'DE-' (often a negative prefix). A delusion is a DEEPLY held false belief, like an illusion that's become dangerously fixed.
Conceptual Metaphor
FALSE BELIEF IS A DISEASE / MENTAL PARASITE (e.g., 'infected by delusions', 'a sick delusion'). REALITY IS SOLID GROUND / LIGHT (e.g., 'lost in delusion', 'free from delusion').
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not confuse with 'иллюзия' (illusion), which is a milder, often pleasant, deception of the senses. 'Delusion' is stronger and pathological. The closer Russian equivalent is 'бред' or 'заблуждение' (though 'заблуждение' can be less severe).
- Avoid directly translating the phrase 'under the delusion' word-for-word; use the structure 'находиться в заблуждении, что...' or 'жить в бредовой уверенности, что...'.
Common Mistakes
- Using 'delusion' to mean a simple mistake or minor misunderstanding (too strong).
- Confusing 'delusion' with 'illusion' (an illusion is a sensory trick; a delusion is a cognitive false belief).
- Incorrect preposition: 'delusion for' instead of 'delusion about' or 'delusion that'.
Practice
Quiz
In a clinical context, which of the following best describes a 'delusion'?
FAQ
Frequently Asked Questions
An 'illusion' is a distortion of the senses, a trick of perception that is usually understood as false once explained (e.g., an optical illusion). A 'delusion' is a fixed false belief held in the mind, often pathologically, despite evidence to the contrary.
Yes, in everyday language it is used metaphorically to describe a strongly held mistaken belief, usually with a critical tone (e.g., 'the delusion of a perfect society').
Yes, 'delusional' is the adjective (e.g., 'a delusional patient', 'delusional thinking'). The rarely used adverb is 'delusionally'.
It is a specific type of delusion where a person believes they have exceptional power, wealth, talent, or importance far beyond reality, commonly seen in conditions like bipolar disorder or schizophrenia.
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