vena cava
Concise Oxford English Dictionary © 2008 Oxford University Press:
vena cava /ˌviːnə ˈkeɪvə/
▶noun (pl. venae cavae /ˌviːniː ˈkeɪviː/) each of two large veins carrying deoxygenated blood into the heart.
– origin C16: from L., lit. ‘hollow vein’.
'vena cava' also found in these Oxford entries:

