
Eyeball
Visual Organ
The word 'eyeball' refers specifically to the spherical part of the eye.
The optometrist examined the health of her eyeballs.
Not the Whole Eye
'Eyeball' does not include the eyelids, eyelashes, or eyebrows; it's just the visible sphere.
His eyeball was irritated, but his eyelids were fine.
Literally Visible
When speaking of 'eyeballs', it sometimes implies the colored part that is visible to others.
Her green eyeballs stood out against her dark makeup.