To present participles which come from intransitive verbs, or are themselves employed as adjectives, to mark the absence of the activity, disposition, or condition implied by the participle;

Not reasonable; irrational; immoderate; exorbitant.

not reasonable; not showing good judgment

pungent adjectives of disesteem; "gave me a cockamamie reason for not going"; "wore a goofy hat"; "a silly idea"; "some wacky plan for selling more books"