adj. very foolish; "harebrained ideas"; "took insane risks behind the wheel"; "a completely mad scheme to build a bridge between two mountains"

adj. affected with madness or insanity; "a man who had gone mad"

adj. not prudent or wise; "very imprudent of her mother to encourage her in such silly romantic ideas"; "would be imprudent for a noneconomist to talk about the details of economic policy"- A.M.Schlesinger

adj. characterized by or arising from psychoneurotic hysteria; "during hysterical conditions various functions of the human body are disordered"- Morris Fishbein; "hysterical amnesia"

adj. not consistent with or using reason; "irrational fears"; "irrational animals"

adj. guided by whim and fancy; "flighty young girls"

adj. guided by whim and fancy; "flighty young girls"

adj. (of especially persons) lacking sense or understanding or judgment

adj. incongruous;inviting ridicule; "the absurd excuse that the dog ate his homework"; "that's a cockeyed idea"; "ask a nonsensical question and get a nonsensical answer"; "a contribution so small as to be laughable"; "it is ludicrous to call a cottage a mansion"; "a preposterous attempt to turn back the pages of history"; "her conceited assumption of universal interest in her rather dull children was ridiculous"

adj. devoid of intelligence

adj. showing or resulting from lack of judgment or wisdom; "an unwise investor is soon impoverished"

adj. poorly conceived or thought out; "an ill-conceived plan to take over the company"

adj. lacking sense or discretion; "his rattlebrained crackpot ideas"; "how rattlepated I am! I've forgotten what I came for"- Glenway Westcott