Origin

The kanji 噴 combines the mouth radical 口 on the left, which classifies this as a word related to speech or things coming out of the mouth, with the component 賁 on the right that serves as a sound hint for the pronunciation フン. The meaning evolved from the basic idea of something forcefully coming out of the mouth — like an eruption or sudden emission of air, liquid, or sound. Over time, this sense of violent expulsion expanded to mean erupting, spouting, or flushing out more generally. The mouth component grounds the character in the physical act of expelling something forcefully.