lobus azygos

[ăzĭ-gŏs′, ā-zī-]
n.
  1. A small accessory lobe sometimes found on the upper part of the right lung, separated from the rest of the upper lobe by a deep groove lodging the azygos vein.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.