1.  ludicrous(s = adj.all) farcical, ridiculous - broadly or extravagantly humorous; resembling farce; "the wild farcical exuberance of a clown"; "ludicrous green hair"

2.  ludicrous(s = adj.all) absurd, cockeyed, derisory, idiotic, laughable, nonsensical, preposterous, ridiculous - 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"

1.  Adapted to excite laughter, without scorn or contempt; sportive. Broome. [1913 Webster]
"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."

2.  Ridiculously absurd. [PJC]

ludicrous, adj. absurd or ridiculous; laughable.

Derivative:
ludicrously adv. ludicrousness n.

Etymology:
L ludicrus prob. f. ludicrum stage play

N  ridiculousness, comicality, oddity, extravagance, drollery, farce, comedy, burlesque, buffoonery, frippery, doggerel verses, absurdity, bombast, anticlimax, bathos, eccentricity, monstrosity, laughingstock, ridiculous, ludicrous, comical, droll, funny, laughable, pour rire, grotesque, farcical, odd, whimsical, whimsical as a dancing bear, fanciful, fantastic, queer, rum, quizzical, quaint, bizarre, screaming, eccentric, strange, outlandish, out of the way, baroque, weird, awkward, extravagant, outre, monstrous, preposterous, bombastic, inflated, stilted, burlesque, mock heroic, drollish, seriocomic, tragicomic, gimcrack, contemptible, doggerel, ironical, risible, risum teneatis amici, rideret Heraclitus, du sublime au ridicule il n'y a qu'un pas.