hippocampus

From Late Latin hippocampus, from Ancient Greek ἱππόκαμπος (hippókampos, from ῐ̔́ππος (hĭ́ppos, “horse”) +‎ κάμπος (kámpos, “sea-monster”)). The anatomy sense is so named from its resemblance to the seahorse. By surface analysis, hippo- +‎ campus.