Origin of adventitia
New Latin, alteration of Latin adventicia, neuter plural of adventicius coming from outside, from adventus, past participle
First Known Use: 1876
Medical Definition of adventitia
: the outer layer that makes up a tubular organ or structure and especially a blood vessel, is composed of collagenous and elastic fibers, and is not covered with peritoneum—called also tunica adventitia, tunica externa
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