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."