The term "jejunum" derives from the Latin "jejunus," which means "empty of food," "meager," or "hungry." The ancient Greeks noticed at death that this part of the intestine was always empty of food. Hence, the name the jejunum.
The Latin "jejunus" also gave rise to "jejune" means lacking in nutritive value and devoid of substance, significance or interest, that is dull. A jejune argument is one that is empty (like the jejunum) and totally devoid of interest.