In anatomy, azygos, from the Greek άζυξ, refers to a structure that is unpaired. This is relatively unusual, as most elements of anatomy reflect
bilateral symmetry. Another term for the same concept is impar.
Well-known structures incorporating this nomenclature include the
azygos veinand ganglion impar.
Also azygos lobe, refers to a normal variant shown in the right upper medial lung
Wikimedia Foundation. 2010.