-vəˈnōsəs noun
Etymology: New Latin, venous sinus
1. : a distinct chamber of the heart formed by the union of the large systemic veins and opening into the auricle in lower vertebrates and the embryos of higher forms
2. : the main cavity of either auricle especially of the human heart
3. : the part of the right auricle between the openings of the venae cavae