ridiculous vs preposterous

ridiculous and preposterous both are adjectives.

Word	Noun	Adjective	Verb	Adverb
ridiculous	No	Yes	No	No
preposterous	No	Yes	No	No

As adjectives, ridiculous and preposterous are synonyms defined as:

Other synonyms of ridiculous include absurd, cockeyed, derisory, idiotic, laughable, ludicrous, nonsensical.

ridiculous (adjective)	preposterous (adjective)
so unreasonable as to invite derision	so unreasonable as to invite derision
broadly or extravagantly humorous; resembling farce
inspiring scornful pity