Definition of: hippocampus

(hip′ə·kam′pəs) noun plural ·pi (-pī)
1. In Greek mythology, a fabulous sea monster with the head and forequarters of a horse and the tail of a dolphin.
2. Anat. One of two eminences found on the floor of the lateral ventricles of the brain. The larger, hippocampus major, is in the descending or temporal cornu of the ventricle; the smaller, hippocampus minor, is in the occipital cornu.
3. The sea horse. [<L <Gk. hippos horse + kampos sea monster]
—hip′po·cam′pal adjective