ventricle
1. A chamber of the heart that receives blood from an atrium and pumps it into the arterial system. Amphibians and fish have a single ventricle, but mammals, birds, and reptiles have two, pumping deoxygenated blood to the lungs and oxygenated blood to the rest of the body, respectively.

2. Any of the four linked fluid-filled cavities in the brain of vertebrates. One of these cavities is in the medulla oblongata, two are in the cerebral hemispheres (see cerebrum), and the fourth is in the posterior part of the forebrain. The ventricles contain cerebrospinal fluid filtered from the blood by the choroid plexus.

ven·tri·cle / ˈventrəkəl/ • n. Anat. a hollow part or cavity in an organ, in particular: ∎  each of the two main chambers of the heart, left and right. ∎  each of the four connected fluid-filled cavities in the center of the brain.DERIVATIVES: ven·tric·u·lar / venˈtrikyələr/ adj.

ventricle (ven-trik-ŭl) n.
1. either of the two lower chambers of the heart. The left ventricle receives blood from the pulmonary vein and pumps it into the aorta. The right ventricle pumps blood from the venae cavae into the pulmonary artery.

2. one of the four fluid-filled cavities within the brain. The paired first and second ventricles (lateral ventricles) communicate with the third ventricle. This leads to the fourth ventricle in the hindbrain, which is continuous with the spinal canal. Cerebrospinal fluid circulates through all the cavities.

ventricle Either of the two lower chambers of the heart. Blood is pumped from the right ventricle to the lungs and from the left ventricle throughout the body.

ventricle (anat.) any of the cavities of the heart, brain, etc. XIV. — L. ventriculus, dim. of venter belly; see -CLE.