(1):

(n.) 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.

(2):

(n.) The siphon of Cephalopoda. See Cephalopoda.

(3):

(n.) A central cavity in the Ctenophora, into which the gastric sac leads.