noun
: a slight elevation that is nearly coextensive with the optic disk and is produced by the thick bundles of the fibers of the optic nerve in entering the eyeball
noun
: a slight elevation that is nearly coextensive with the optic disk and is produced by the thick bundles of the fibers of the optic nerve in entering the eyeball
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012