1. A funnel or funnel-shaped structure or passage. 2. The expanding portion of a calyx as it opens into the renal pelvis. 3. Termination of a bronchiole in the alveolus. 4. Termination of the cochlear canal beneath the cupola. 5. The funnel-shaped, unpaired prominence of the base of the hypothalamus behind the optic chiasm, enclosing the infundibular recess of the third ventricle and continuous below with the stalk of the hypophysis.