Definitions

1. adjective

relating to or located near the outer layer of a structure, such as a blood vessel or a joint, especially the connective tissue that surrounds it.

“The adventitial layer of the artery helps regulate blood pressure and flow.”

2. noun

a tissue or structure that is located near the outer layer of a structure, such as a blood vessel or a joint.

“The adventitia is the outermost layer of a blood vessel wall, surrounding the media and intima.”