azygos vein

 
Pronunciation: /ˈazɪgəs/

noun

Anatomy
  • a large vein on the right side at the back of the thorax, draining into the superior vena cava.

Origin:

mid 17th century: azygos from Greek azugos, from a- 'without' + zugon 'yoke', the vein not being one of a pair