so unreasonable as to invite derision
"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"
Pertaining to or resembling an idiot; characterised with behaviour resembling idiocy.