Old English bealcan "bring up wind from the stomach," also "swell, heave," of echoic origin (compare Dutch balken "to bray, shout"). Extended to volcanoes, cannons, etc. 1570s. Related: Belched; belching. As a noun, "an act of belching," it is recorded from 1510s; also slang for "poor beer, malt liquor" (1706).