ven·tri·cle 
(vĕntrĭ-kəl)
(vĕntrĭ-kəl)n.
A small cavity or chamber within a body or organ, especially:
a. The chamber on the left side of the heart that receives arterial blood from the left atrium and contracts to force it into the aorta.
b. The chamber on the right side of the heart that receives venous blood from the right atrium and forces it into the pulmonary artery.
c. Any of the interconnecting cavities of the brain.
[Middle English, from Old French ventricule, from Latin ventriculus, diminutive of venter, belly.]