n. (pl. hippocampi) 1 any marine fish of the genus Hippocampus, swimming vertically and with a head suggestive of a horse; a sea horse. 2 Anat. the elongated ridges on the floor of each lateral ventricle of the brain, thought to be the centre of emotion and the autonomic nervous system.
[ L f. Gk hippokampos f. hippos horse + kampos sea monster ]