define infundibulum
â¦way to the lungsâor the infundibulum, or of both. The infundibulum (Latin: âfunnelâ) is the funnel-shaped portion of the right ventricle that opens into the pulmonary artery. Its narrowing is also called infundibular stenosis. Pulmonary stenosis is usually a congenital defect and may be associated with other cardiovascular congenital defects.