1. [ adjective ] insanely irresponsible
Synonyms: crackbrained

"an idiotic idea"

Related terms: insane
2. [ adjective ] having a mental age of three to seven years
Synonyms: imbecilic imbecile
Related terms: unintelligent
3. [ adjective ] completely devoid of wisdom or good sense
Synonyms: ridiculous preposterous absurd laughable nonsensical cockeyed ludicrous derisory

"the absurd excuse that the dog ate his homework" "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"

Related terms: foolish