The term VENA CAVA NEIGHBOR refers to the AORTA, which is a 5-letter word. The AORTA is the largest artery in the human body and is located in the chest and abdomen. It carries oxygenated blood from the heart to the rest of the body. The vena cava is the largest vein in the body and is located in the chest and abdomen. It carries deoxygenated blood from the body back to the heart. The AORTA and vena cava are neighbors in the body, as they are both located in the chest and abdomen.