The Oxford Thesaurus An A-Z Dictionary of Synonyms - maniacaladj.

1) manic, maniac, insane, lunatic, mad, demented, deranged, hysterical, mentally ill, of unsound mind, non compos mentis, psychotic: He had to be hospitalized because of his maniacal behaviour. 2) hysterical, berserk, wild, crazy, Slang loony: His maniacal outbursts frightened us.