What is the X in X-mas?
Old English bealcan "bring up wind from the stomach," also "swell, heave," of echoic origin (cf. Dutch balken "to bray, shout"). Extended to volcanoes, cannons, etc. 1570s. Related: Belched; belching. As a noun, recorded from 1510s. It is recorded in 1706 as a slang noun meaning "poor beer."
v. belched, belch·ing, belch·es
To expel stomach gas noisily through the mouth; burp.