Source : Webster's Revised Unabridged Dictionary (1913)

Idiotic \Id`i*ot"ic\, Idiotical \Id`i*ot"ic*al\, a. [L.
   idioticus ignorant, Gr. ?: cf. F. idiotique. See {Idiot}.]
   1. Common; simple. [Obs.] --Blackwall.

   2. Pertaining to, or like, an idiot; characterized by idiocy;
      foolish; fatuous; as, an idiotic person, speech, laugh, or
      action.

Source : WordNet®

idiotic
     adj 1: insanely irresponsible; "an idiotic idea" [syn: {crackbrained}]
     2: completely devoid of wisdom or good sense; "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" [syn: {absurd}, {cockeyed}, {derisory},
         {laughable}, {ludicrous}, {nonsensical}, {preposterous},
        {ridiculous}]
     3: having a mental age of three to seven years [syn: {imbecile},
         {imbecilic}]