n. The little brain or hind-brain of a vertebrate animal; a lobe of the brain developed on the dorsal side of the cerebrospinal axis, between the corpora quadrigemina in front and the medulla oblongata behind, and forming part of the roof of the fourth ventricle.n. In Insecta, the subesophageal ganglion, situated in the lower part of the head, and connected with the supra-esophageal ganglion or cerebrum by two nerve-chords surrounding the gullet