Meaning

noun a reflex that expels gas noisily from the stomach through the mouth

verb expel gas from the stomach

verb become active and spew forth lava and rocks

originFrom Middle English belchen, from Old English bielċan, from Proto-Germanic *balkijaną, *belkaną, probably ultimately of imitative origin. Related to Dutch balken (“to bray”), Middle Low German belken (“to shout”), Low German bölken (“to shout, bark”), Old English bealċettan (“to utter, send forth”). See also English bolk, boak.

Etymology from Wiktionary, CC BY-SA 3.0