insane

adjective

in·​sane (ˌ)in-ˈsān 

1

a(1)

dated, now usually offensive : exhibiting a severely disordered state of mind

(2)

law : affected with insanity (see insanity sense 2)

criminally insane

b

: unable to think in a clear or sensible way

insane with jealousy

—not used technically

2

now usually offensive : used by, typical of, or intended for people having a severely disordered state of mind

an insane asylum

3

: absurd

an insane scheme for making money

4

: outrageously high or extreme

making insane amounts of money

The monster truck pursued him at insane speeds …

—Hunter S. Thompson

More than 22,000 athletes descend on Philadelphia's Franklin Field to chug insane amounts of Gatorade …

—Chris Ballard

also : exceptionally good or impressive

Minnesota … has blazed out to an insane start, taking an early lead in the Northwest Division.

—Tom Wheatley

With his rough-edged baritone and ear for insane hooks, [reggae singer] Baby Cham always sounds wicked.

—Rob Kenner

insaneness

(ˌ)in-ˈsān-nəs 

noun

Synonyms of insane

• mad
• maniacal
• crazy
• mental
• nuts

Examples of insane in a Sentence

The murderer was found to be criminally insane.

She was insane with jealousy.

He had an insane look in his eyes.

She likes to drive at insane speeds.

He had this insane idea that he could get rich by selling old computers.

Recent Examples on the Web

At 5-foot-8 and 140 pounds, Keira is the first to admit she’s not blessed with insane athletic ability. —Don Norcross, San Diego Union-Tribune, 12 Jan. 2026

His insane policies on immigration, health and climate, and military actions against sovereign nations has led to the insanity happening in this country. —Sun Sentinel Editorial Board, Sun Sentinel, 12 Jan. 2026

Or why roads and other critical infrastructure projects now take untold years and insane amounts of money to complete, and by the time they are finally opened are already rendered all but obsolete? —Lee Steinhauer, The Orlando Sentinel, 11 Jan. 2026

In this abjectly insane political environment that Minnesotans have created for themselves, the federal agent has about as much chance of a fair trial as the Vikings have of winning this year’s Super Bowl, which is to say, none. —David Marcus, FOXNews.com, 10 Jan. 2026

Word History

Etymology

Latin insanus, from in- + sanus sane

First Known Use

1575, in the meaning defined at sense 1a(1)

Phrases Containing insane

• go insane
• insane asylum
• the insane

Rhymes for insane

• abstain
• airplane
• alkane
• arcane
• arraign
• attain
• backplane
• betaine
• biplane
• blockchain
• butane
• campaign

Kids Definition

insane

adjective

in·​sane (ˈ)in-ˈsān 

1

usually offensive : having or showing a severely disordered state of mind : not sane

—used especially in the past

an insane person

an insane look

2

usually offensive : used by or for people having a severely disordered state of mind

an insane ward in a hospital

3

: extremely foolish or unreasonable

an insane attempt

insanely adverb

Medical Definition

insane

adjective

in·​sane (ˈ)in-ˈsān 

1

dated, now usually offensive : exhibiting a severely disordered state of mind

2

law : affected with insanity (see insanity sense 2)

insanely adverb

Legal Definition

insane

adjective

in·​sane

: affected with insanity