Cerebellum \Cer`e*bel"lum\, n.; pl. E. Cerebellums, L. Cerebella. [L., dim. of cerebrum brain.]

(Anat.) The large lobe of the hind brain in front of and above the medulla; the little brain. It controls combined muscular action. See Brain.

Source: Webster's Revised Unabridged Dictionary (1913)