orifice (or'if-is)

The anus, aortic See o. opening, analo. o. The circular in the left ventricle connecting it with the aorta, auriculoventricular o. 1. An oval opening in the lower and front part of the left auricle, leading into the left ventricle of the heart. 2. An oval opening situated at the right angle of the base of the right ventricle of the heart and leading into the right auricle, cardiac o. of the stomach. The o. in the cardiac end of the stomach where the esophagus enters it. mitral o. See auriculoventricular o. (1st def.). o. of the coronary sinus of the right auricle. An o. situated between that of the inferior vena cava and the auriculoventricular o. pulmonary o. An o. in the left angle of the base of the right ventricle of the heart and leading into the pulmonary artery, pyloric o. See pylorus. [Lat., oriUcium, from os, or is, mouth, + facer e, to make.]