There are many synonyms for the word "belter," which can be used to refer to something that is excellent or impressive. Some popular synonyms for this word include "smasher," "hit," "winner," "blockbuster," "smash hit," and "triumph." Each of these words has its own unique connotations and associations, but they are all generally used to describe something that is exceptional in some way. Other synonyms for "belter" include "stunner," "gem," "jewel," and "treasure," all of which suggest that the thing being described is of great value or importance. These different synonyms can be used interchangeably depending on the context and the tone of the writing or speech.