In 1850 it was observed that U.S. senators from opposing political parties would often come together to share snuff, and "forget their sectional differences in a delightful concert of sternutation." (Snuff as an aid to democracy?)
From the Greek word meaning "to rumble." Borborygmus is onomatopoeic - because it sounds, at least to the Ancient Greeks, just like the thing it describes.
This is one source of that great poetic outflow of words and phrases ("technicolor yawn," etc.) created to describe this event. The Greek root is merely emein, which is not nearly as inspired as borborygmus, the previous word in this list.