A cavity, or one of the cavities, of an organ, as of the larynx or the brain; specifically, the posterior chamber, or one of the two posterior chambers, of the heart, which receives the blood from the auricle and forces it out from the heart. See Heart.
- A small cavity or chamber within a body or organ, especially:
- 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.
- The chamber on the right side of the heart that receives venous blood from the right atrium and forces it into the pulmonary artery.
- Any of the interconnecting cavities of the brain.