adventitia
— Noun
– English
～ an enveloping or covering membrane or layer of body tissue
adventitial
— Adjective
– English
～ of or pertaining to the adventitia
adventitious
— Adjective
– English
～ associated by chance and not an integral part; "poetry is something to which words are the accidental, not by any means the essential form"- Frederick W. Robertson; "they had to decide whether his misconduct was adventitious or the result of a flaw in his character"