an insane person.

a person whose actions and manner are marked by extreme eccentricity or recklessness.

Law . a person legally declared to be of unsound mind and who therefore is not held capable or responsible before the law.

insane; demented; crazy.

characteristic or suggestive of lunacy; wildly or recklessly foolish.

designated for or used by the insane

a lunatic asylum.

gaily or lightheartedly mad, frivolous, eccentric, etc.

She has a lunatic charm that is quite engaging.

adjective

healthy , sane , sensible

noun

sane

adjective

absurd , baked * , balmy * , bananas , bonkers * , cracked , crazed , daft , demented , deranged , dippy , flaky * , flipped out , foolish , freaked out , fried * , idiotic , insane , irrational , kooky , loco , maniac , maniacal , nonsensical , nutty * , preposterous , psyched out , psychotic , schizoid , screwy * , stupid , unsound , whacko , zany , brainsick , crazy , disordered , distraught , dotty , mad , mentally ill , moonstruck , off , touched , unbalanced , wrong , harebrained , imbecilic , moronic , silly , softheaded , tomfool , unearthly

noun

crackpot * , crank , cuckoo * , demoniac , flake * , fruitcake , kook * , lamebrain * , loon , maniac , neurotic , nut * , paranoid , psycho , psychopath , psychotic , scatterbrain , schizophrenic , sociopathic , crazy , eccentric , bananas , batty , bedlamite , bonkers , crackpot , cuckoo , deranged , insane , irrational , kooky , loco , loony , mad , madman , maniacal , nutty , screwball , unsound , wacky , zany