What is the term used to describe the actual "eyeball"?

The term used to describe the actual "eyeball" is "globe." In anatomical terminology, the globe refers specifically to the spherical shape of the eye that comprises various structures involved in vision, including the cornea, lens, and retina. Understanding this term is important in the context of optics because it helps differentiate between the physical structure of the eye and other components that play roles in vision but are not part of the eyeball itself.

The optic nerve refers to the bundle of nerve fibers that transmits visual information from the retina to the brain but does not represent the eyeball itself. The fibrous tunic is the outer layer of the eye that includes the sclera and cornea, providing structure and protection but does not denote the whole eyeball. The ciliary body, part of the eye that helps control focus and produces aqueous humor, is also a component of the eye, but not the actual globe. Therefore, "globe" accurately captures the overall structure you are referring to when discussing the "eyeball."