In the parsha of sotah (Bamidbar 5:13) the Torah describes the woman who was secluded and had relations with another man as וְנִסְתְּרָ֖ה וְהִ֣יא נִטְמָ֑אָה meaning that she became physically defiled - ie had (extra)marital relations. To my knowledge the term tumah relates specifically to spiritual impurity. I would like to know if the Torah uses this term to describe physical impurity/defilement anywhere else besides by sotah and if not, why the term was used here?
I have seen the commentary of Hizkuni who implies that the term was used because she became ta'meh through semen, however I believe that the gemarah stipulates the woman can become ta'meh (in terms of a sotah) even if there is no g'mar be'ah, therefore I would like to find an alternative answer.