belch

(noun) a reflex that expels gas noisily from the stomach through the mouth. Synonyms: belching, burp, burping, eructation.

(verb) expel gas from the stomach. Synonyms: burp, bubble, eruct. Example: "In china it is polite to burp at the table."

(verb) become active and spew forth lava and rocks. Synonyms: erupt, extravasate. Example: "Vesuvius erupts once in a while."