insane
gb/ɪnsˈeɪn/ us/ɪnsˈeɪn/
B1
English
~ 1900
Senses
0 senses
adjective
informal
B1
property
1
Extremely foolish or unreasonable
Very silly or unreasonable; not making sense.
Usage pattern:
[someone/something] is insane
Common mistake:
Learners sometimes confuse this meaning with the medical sense of 'mentally ill', which is less common in everyday speech.
Synonyms
crazy (Common informal synonym; slightly more casual and versatile.)
|
ridiculous (Focuses on being absurd rather than irrational.)
Antonyms
sensible (Emphasizes sound judgment and reason, the opposite of foolishness.)
Collocations
insane idea
|insane plan
|insane amount
|insane price
|insane speed
Themes
emotions
|daily life
|communication
|core_vocabulary
Examples
- That was an insane amount of money to spend on shoes.
- Driving that fast in the rain is insane.
- The plot twist in the movie was absolutely insane.
Learner examples
- It is insane to walk on the road at night without lights.
- That game was insane and very exciting.
- He paid an insane price for the watch.
adjective
B2
state
2
Having a severe mental illness
Having a serious mental illness that changes how someone thinks or acts.
Usage pattern:
[someone] is insane
Common mistake:
Learners often overuse this meaning in casual contexts where 'crazy' or 'ridiculous' would be more appropriate.
Synonyms
psychotic (Medical term referring to severe mental disorders involving loss of contact with reality.)
Antonyms
sane (Means having normal mental health and sound judgment.)
Collocations
legally insane
|declared insane
|mentally insane
Themes
health
|law
|emotions
Examples
- The court found him legally insane at the time of the crime.
- She was diagnosed as insane after a long evaluation.
- They claimed he was insane and needed treatment.
Learner examples
- The man was declared insane by the doctor.
- She is insane and cannot take care of herself.
- The judge said he was legally insane.
adjective
informal
B2
property
3
Extremely impressive or exciting
Very exciting or amazing; hard to believe because it is so good or extreme.
Usage pattern:
[something] is insane
Common mistake:
Learners may confuse this with the negative senses of 'insane', but here it is positive slang for 'amazing'.
Synonyms
amazing (Highlights admiration without the informal exaggeration.)
|
incredible (Focuses on being hard to believe due to excellence.)
Antonyms
boring (Describes something dull and unexciting, opposite in emotional impact.)
Collocations
insane performance
|insane talent
|insane skill
Themes
emotions
|entertainment
|core_vocabulary
|communication
|arts_entertainment
Examples
- The guitarist gave an insane performance last night.
- That roller coaster has some insane drops.
- Her cooking skills are absolutely insane.
Learner examples
- The show last night was insane.
- He has insane skills in basketball.
- The party was insane and fun.
Grammar
Dictionary form
insane
IPA
GB/ɪnsˈeɪn/
US/ɪnsˈeɪn/
Syllables & stress
in - sane (2 syllables)
Stress on 2nd syllable (sane)
Word forms
Adjective
- Base: insane
Word family
Core family
insanely
adverb
insanity
noun
Negative and opposite forms
Expressions
drive someone insane
1/dɹˈaɪv sˈʌmwˌʌn ɪnsˈeɪn/
idiom
informal
Make someone extremely annoyed or stressed
To make someone feel very annoyed, upset, or mentally tired.
Examples
- The constant noise is driving me insane.
- Her endless questions were driving him insane.
go insane
1/ɡˈoʊ ɪnsˈeɪn/
fixed phrase
Become mentally ill or irrational
To become mentally ill or start acting in a very strange way.
Examples
- He nearly went insane after months of isolation.
- She thought she would go insane if the noise didn’t stop.
insane asylum
1/ɪnsˈeɪn əsˈaɪləm/
fixed phrase
archaic
Old term for psychiatric hospital
An old term for a hospital where people with serious mental illness lived and got treatment.
Examples
- In the past, many were sent to an insane asylum for life.
- The horror film is set in an abandoned insane asylum.
- The novel is set in an old insane asylum.
- In the early 1900s, many people were sent to insane asylums for minor conditions.