preposterous vs ridiculous

preposterous and ridiculous both are adjectives.

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

As adjectives, preposterous and ridiculous are synonyms defined as:

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

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