Un-alterably is a word that describes something that is unable to be changed or altered. The meaning of this word can be conveyed in many other ways through synonyms. Some possible synonyms for un-alterably include immutably, irrevocably, permanently, fixedly, steadfastly, resolutely, and conclusively. These words all convey a sense of permanence and stability, indicating that something cannot be changed. Whether you are describing an unalterable decision or a situation that cannot be altered, using one of these synonyms can help to strengthen your writing and convey a clear sense of the unchangeable nature of the situation.