Ludicrous means laughingly absurd or ridiculous.
Ludicrous is an adjective.
Synonyms: crazy, nonsensical, outlandish, preposterous.
Antonyms: sensible, logical, reasonable.
1. We all agreed that hiding the book in the shelf was ludicrous; hiding it under the bed was a much more reasonable plan.
2. Mr. Ravi's plan is ludicrous — outlandish and laughable.
3. I don't think that my request for raising the salary is ludicrous. I think it is quite reasonable.