UPDATED: The root term [-zyg-] originates from the Greek [ζεύγος] meaning "a pair", as in a yoke. Applications of this root term include:

• Azygos: The prefix [a-] means "no", "not", or "without". Not paired or unyoked. The azygos system of veins, found in the posterior aspect of the mediastinum, is not symmetrical. It is therefore "unpaired". It is composed of dissimilar contralateral components which include the azygos vein on the right side, and the hemiazygos and accessory hemiazygos on the left side.
• Hemiazygos: The prefix [-hemi-] means "half". Half unpaired or unyoked. Refers to the contralateral component of the azygos system of veins.
• Zygapophysis: Click on the link for more information. Paired (bilateral) bony articular protrusions in the posterior aspect of the vertebrae

Important note to medical writers: The word is "azygos", not "azygous"

Note: The links to Google Translate in these articles include an icon that will allow you to hear the Greek or Latin pronunciation of the word.