Belch out is a phrase that refers to the act of expelling gas, usually from the mouth in a loud and rude manner. However, there are several synonyms that can be used to describe this action. Some of the synonyms for belch out include burp, eructate, gurgle, grumble, rumble, and spew. These words all describe the same action of expelling gas from the mouth or stomach, but they provide different levels of emphasis on the sound or odor associated with the action. Regardless of the word used, belching is generally considered an impolite and unpleasant habit that should be avoided in social situations.