insane

//ɪnˈseɪn//
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Visual representation of insane

Adjective

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1

Mentally ill; suffering from a serious mental disorder that affects one's ability to think rationally or behave normally.

He was declared legally insane and sent to a psychiatric hospital.

2

Extremely foolish, irrational, or unreasonable; lacking common sense.

It's insane to drive in this weather without snow tires.

3

Extremely excessive or extreme in degree; outrageous.

The prices at that restaurant are insane.