in·sane 
/ɪnˈseɪn/ adjective
/ɪnˈseɪn/ adjective 1 [more insane; most insane] : not sane: such as a : having or showing severe mental illness
▪ an insane person ▪ The murderer was found to be criminally insane.
b : unable to think in a clear or sensible way
▪ She was insane with jealousy/anger.
c — used in the phrase drive/make (someone) insane to describe annoying or bothering someone very much. ▪ That noise is driving me insane. [=it is annoying me very much] ▪ It makes me insane [=I feel very annoyed] when people drive like that. 2 : wild and uncontrolled
▪ He had an insane look in his eyes. 3 [more insane; most insane] : very foolish or unreasonable : crazy
▪ She likes to drive at insane speeds. ▪ He had this insane idea that he could get rich by selling old computers. 4 : used for people who have severe mental illnesses
▪ an insane asylum [=(now more commonly) a mental hospital]
▪ an insane person ▪ The murderer was found to be criminally insane.
usage The use of insane to describe a person with severe mental illness is now often considered offensive. The phrase mentally ill is preferred. Insane in this sense now occurs chiefly in such legal phrases as criminally insane and temporarily insane.
b : unable to think in a clear or sensible way
▪ She was insane with jealousy/anger.
c — used in the phrase drive/make (someone) insane to describe annoying or bothering someone very much. ▪ That noise is driving me insane. [=it is annoying me very much] ▪ It makes me insane [=I feel very annoyed] when people drive like that.
▪ 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.
▪ an insane asylum [=(now more commonly) a mental hospital]
go insane
: to become mentally ill : to go crazy
▪ She went insane and started thinking that everyone was trying to kill her. — usually used in an exaggerated way ▪ I must be going insane. I can't find my car keys anywhere. ▪ If you don't stop making that noise, I'm going to go (completely) insane!
▪ She went insane and started thinking that everyone was trying to kill her. — usually used in an exaggerated way ▪ I must be going insane. I can't find my car keys anywhere. ▪ If you don't stop making that noise, I'm going to go (completely) insane!
the insane
: insane people : people who have severe mental illness
▪ a hospital for the insane [=(now more commonly) the mentally ill]
▪ a hospital for the insane [=(now more commonly) the mentally ill]
— in·sane·ly adverb
▪ Her boyfriend was insanely jealous.
▪ Her boyfriend was insanely jealous.
