Source : Webster's Revised Unabridged Dictionary (1913)

Ridiculous \Ri*dic"u*lous\, a. [L. ridiculosus, ridiculus, fr.
   ridere to laigh. Cf. {Risible}.]
   1. Fitted to excite ridicule; absurd and laughable; unworthy
      of serious consideration; as, a ridiculous dress or
      behavior.

            Agricola, discerning that those little targets and
            unwieldy glaives ill pointed would soon become
            ridiculous against the thrust and close, commanded
            three Batavian cohorts . . . to draw up and come to
            handy strokes.                        --Milton.

   2. Involving or expressing ridicule. [r.]

            [It] provokes me to ridiculous smiling. --Shak.

   Syn: Ludicrous; laughable; risible; droll; comical; absurd;
        preposterous. See {Ludicrous}. --- {Ri*dic"u*lous*ly},
        adv. -- {Ri*dic"u*lous*ness}, n.

Source : WordNet®

ridiculous
     adj 1: inspiring scornful pity; "how silly an ardent and
            unsuccessful wooer can be especially if he is getting
            on in years"- Dashiell Hammett [syn: {pathetic}, {silly}]
     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}, {ludicrous}, {nonsensical}, {preposterous}]
     3: broadly or extravagantly humorous; resembling farce; "the
        wild farcical exuberance of a clown"; "ludicrous green
        hair" [syn: {farcical}, {ludicrous}]