Definition of Adventitious

Adventitious: Coming from an external source or occurring in an unusual place or manner. Not inherent, inherited or innate but rather occurring accidentally or spontaneously.
When a doctor or nurse auscults (listens to) the chest or abdomen, adventitious sounds are those that are normally not heard coming from the chest or abdomen.
The word "adventitious" comes from the Latin "adventicius" meaning "foreign, strange, extraneous, coming from abroad or from outside." This, in turn, comes from the verb "advenire" meaning "to come to" or "to arrive." Other English words that stem from "advenire" include "adventure," "avenue," and the medical term "adventitia."

Definition of Abdomen

Abdomen: The belly, that part of the body
that contains all of the structures between the chest and
the pelvis. The abdomen is separated anatomically from the chest
by the diaphragm, the powerful muscle spanning the body cavity below the lungs.
The abdomen includes a host of organs including the stomach, small intestine, colon, rectum, liver, spleen, pancreas, kidneys, appendix,
gallbladder, and bladder.
The word "abdomen" has a curious story behind it. It comes
from the Latin "abdodere", to hide. The idea was that whatever was
eaten was hidden in the abdomen.