a funnel-shaped or dilated organ or part; as, the infundibulum of the brain, a hollow, conical process, connecting the floor of the third ventricle with the pituitary body; the infundibula of the lungs, the enlarged terminations of the bronchial tubes.-a central cavity in the ctenophora, into which the gastric sac leads.-the siphon of cephalopoda. see cephalopoda.