not sane; not of sound mind; mentally deranged.

of, pertaining to, or characteristic of a person who is mentally deranged

insane actions; an insane asylum.

utterly senseless

an insane plan.

adjective

balanced , healthy , rational , reasonable , sane , sound , well

adjective

batty * , bizarre , cracked * , crazed , crazy , cuckoo * , daft , demented , derailed , deranged , fatuous , frenzied , idiotic , impractical , irrational , irresponsible , loony * , lunatic , mad , maniacal , mental , moonstruck , nuts * , nutty * , off one’s rocker , of unsound mind , out of one’s mind , paranoid , preposterous , psychopathic , psychotic , rabid , raging , raving , schizophrenic , screwy , senseless , touched , unhinged , unsettled , wildnotes:inane means silly , lacking significance or insubstantial; insane means mentally deranged , mad or very foolish , brainsick , disordered , distraught , dotty , maniac , mentally ill , off , unbalanced , unsound , wrong , absurd , harebrained , imbecilic , moronic , nonsensical , silly , softheaded , tomfool , unearthly , zany , batty , berserk , chaotic , compulsive , cuckoo , daffy , delirious , dementate , dithyrambic , eccentric , frantic , frenetic , immoderate , incompetent , loco , loony , manic , non compos mentis , nuts , paranoiac , wacky