Dictionary.net

Of or pertaining to the aorta, as A. aneurysm; surrounding the aorta, AR A. plexus (of the sympathetic). A. valves, the three semilunar valves closing the passage (A. opening) between the aorta and the left ventricle. Hence, A. murmur, a murmur indicative of disease of these valves (A. valvular disease). This is either Direct (systolic or obstructive), heard with the first sound of the heart (in which case it is often inorganic), or Regul gitant (indirect or diastolic). See Murmur. A. arches, see Arch.

Of, or pertaining to, the aorta.