The word "belters" usually refers to something that is excellent or outstanding. However, if you want to amplify your vocabulary, there are several other synonyms that you can use. For instance, you can say that something is amazing, astounding, fabulous, incredible, marvelous, or splendid. Other options include exceptional, remarkable, breathtaking, awe-inspiring, or mind-blowing. If you are looking for more casual words, you can use awesome, epic, or wicked. Whatever word you choose, it is always good to have a variety of synonyms at your disposal to make your writing or speaking more interesting and diverse.