In medicine, "adventitious" and related words such as Adventitia refer in various senses to the basic meanings associated with the root in senses such as: "of the nature of a later addition from without, accidental, casual".
In medicine, "adventitious" and related words such as Adventitia refer in various senses to the basic meanings associated with the Latin root "advenire". Typically the general intention is to convey something like: "of the nature of a later addition from without, accidental, casual".