You searched for: “adventitia
adventitia (s) (noun) (no countable)
A membrane that covers an organ but is not part of that organ: Adventitia is primarily made up of connective tissue.

The layer known as adventitia is a pliable sheet of tissue that overlays, lines, or connects the organs or cells of animals or plants.

This entry is located in the following units: ad- (page 10) -al; -ial, -eal (page 7)