通奸罪 is a legal term meaning 'the crime of adultery' or 'adultery as a criminal offense.' It is a formal, legalistic compound (通奸 'adultery' + 罪 'crime') used in law, court rulings, and historical or comparative legal discussions. Note that in modern mainland China, adultery is not a criminal offense under the Criminal Law (though it may have civil consequences in divorce), so the term appears more in historical contexts, legal theory, or in jurisdictions where it remains a crime (e.g., Taiwan, some U.S. states).