n. A court or hall.n. [NL.] In anatomy, the anterior portion of the third ventricle of the brain, corresponding to the cavity of the primitive prosencephalon; a mesal portion of the common ventricular cavity of the brain; in the amphibian brain, the ventricle of the unpaired cerebral rudiment.n. 3. [NL.] In zoology, the cavity of a colony of infusorians, as members of Volvox or Eudorina. A. Hyatt.