The Oxford Thesaurus An A-Z Dictionary of Synonyms - madness n.

1) insanity, lunacy, mania, dementia, psychosis, mental illness: That form of madness is called schizophrenia. 2) craziness, lunacy, folly, foolishness, nonsense, senselessness, ridiculousness, pointlessness, illogicality, illogic, illogicalness, impracticality, preposterousness, futility: He soon realized the madness of trying to stem the tide of public opinion.