adj
insane
ihn-SAYN
adj
1
Suffering from serious mental illness; not of sound mind.
"He was declared legally insane and unfit to stand trial."
2
Extremely foolish, reckless, or impractical.
"It would be insane to quit your job with no savings."
"Driving in that storm is insane."
3
(informal) Extremely impressive, intense, or extraordinary.
"The view from the summit was insane."
How to Use Insane
Learner’s notesIn plain EnglishMentally unwell, or (casually) crazy/reckless, or (slang) amazingly good or intense.
When to use it
The mental-illness sense is now considered outdated and stigmatizing in clinical contexts; the casual senses (reckless, amazing) are common in everyday speech.
Common pairings
legally insane
go insane
insane amount of
Word Forms
more insane comparative, insaner comparative, most insane superlative, insanest superlative
Study it as flashcards or scroll it in Flow — saved to your collection.
Test yourself on “insane”
A quick quiz — meaning, synonyms & usage
→
Fill the Gap
Can you complete this real example?
He was declared legally _____ and unfit to stand trial.
Etymology
From Latin insanus, "unsound in mind" — in- ("not") plus sanus ("sound, healthy").