An eye.
"The optic nerve transmits visual information from the retina to the brain."
of or relating to or resembling the eye
"ocular muscles"
"an ocular organ"
"ocular diseases"
"the optic (or optical) axis of the eye"
"an ocular spot is a pigmented organ or part believed to be sensitive to light"
"ophthalmic defect"
Of, or relating to the eye or to vision.
"The optic nerve transmits visual information from the retina to the brain."
In plain English: Something that is optic relates to your eyesight or how you see things with your eyes.
"The optic nerve sends visual signals from your eye to your brain."
Usage: Use optic as an adjective specifically when describing parts of the eye itself or instruments designed to aid vision, such as an optic nerve or optic fiber. Avoid confusing it with optical, which refers more broadly to anything related to light and lenses rather than just biological structures.
The word optic entered English through Middle French and Medieval Latin. It ultimately comes from Ancient Greek, where it originally meant "of or for sight."