Source : Webster's Revised Unabridged Dictionary (1913)

Ludicrous \Lu"di*crous\, a. [L. ludicrus, or ludicer, from ludus
   play, sport, fr. ludere to play.]
   Adapted to excite laughter, without scorn or contempt;
   sportive. --Broome.

         A chapter upon German rhetoric would be in the same
         ludicrous predicament as Van Troil's chapter on the
         snakes of Iceland, which delivers its business in one
         summary sentence, announcing, that snakes in Iceland --
         there are none.                          --De Quincey.

   Syn: Laughable; sportive; burlesque; comic; droll;
        ridiculous.

   Usage: {Ludicrous}, {Laughable}, {Ridiculous}. We speak of a
          thing as ludicrous when it tends to produce laughter;
          as laughable when the impression is somewhat stronger;
          as ridiculous when more or less contempt is mingled
          with the merriment created. -- {Lu"di*crous*ly}, adv.
          -- {Lu"di*crous*ness}, n.

Source : WordNet®

ludicrous
     adj 1: broadly or extravagantly humorous; resembling farce; "the
            wild farcical exuberance of a clown"; "ludicrous green
            hair" [syn: {farcical}, {ridiculous}]
     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},
         {idiotic}, {laughable}, {nonsensical}, {preposterous}, {ridiculous}]