Synonyms for Ludicrous (same or very similar meaning)
WordNet sense 1 (incongruous;inviting ridicule):
absurd, cockeyed, derisory, idiotic, laughable, nonsensical, preposterous, ridiculousWordNet sense 2 (devoid of good sense or judgment):
foolishWordNet sense 3 (broadly or extravagantly humorous; resembling farce):
farcicalWordNet sense 4 (full of or characterized by humor):
humourousFrom the ODE community, based on WordNetadd/edit