The word "unapprovable" refers to something that cannot be approved or sanctioned. When seeking alternative words to convey a similar meaning, one could use synonyms such as unacceptable, disapproved, non-sanctioned, unratifiable, unendorsed, or unsanctionable. Depending on the context of the sentence, one could also use words such as unattainable, impossible, or unreachable to better capture the intended meaning of the sentence. By using carefully chosen synonyms, one can help to more effectively convey their intended message and ensure that their writing is precise and effective.