What is the history of the term “azygos vein” in the anatomical terminology?

The term “azygos vein” is in common use in modern anatomical and cardiovascular textbooks to describe the vein which ascends to the right side of the vertebral column in the region of the posterior mediastinum draining into the superior vena cava. “Azygos” in Greek means “without a pair”, explaining the lack of a similar vein on the left side of the vertebral column in the region of the thorax. The term “azygos” vein was utilized firstly by Galen and then was regenerated during Sylvius’ dissections and Vesalius’ anatomical research, where it received its final concept as an official anatomical term. The purpose of this study is to highlight the origin of the term “azygos vein” to the best of our knowledge for the first time and its evolution from the era of Hippocrates to Realdo Colombo.