1. Not paired; occurring singly rather than in pairs.
Usage: medical/anatomical term

1. A vein in the thorax that runs along the right side of the vertebral column and drains into the superior vena cava.
Usage: anatomy; full name: azygos vein

Examples

• The azygos vein is an unpaired vessel that plays an important role in venous drainage.
• In anatomy class, students learn that the azygos system includes several azygos veins on the right side of the body.
• The azygos vein runs parallel to the vertebral column.
• Unlike most veins, the azygos is azygos in nature, meaning it has no corresponding pair on the left side.
• Radiologists often identify the azygos vein on chest X-rays as a small rounded opacity near the right tracheobronchial angle.