"Ill-devised" can be replaced by the synonyms "malformed," "injudicious," "improvident," "unwise," "misconceived," "poorly thought out," "ill-considered," "ill-conceived," "unplanned," and "unintentional." All of these words convey the same meaning as "ill-devised," which refers to something that has been poorly or inadequately planned or thought out. These synonyms are useful when you want to add variety to your writing or when you want to find a word that better suits the context in which you are writing. Whatever synonym you choose, it is essential to use it properly to convey the intended message effectively.