op·tic / ˈäptik/ • adj. of or relating to the eye or vision.• n. 1. a lens or other optical component in an optical instrument.2. archaic or humorous the eye.ORIGIN: late Middle English: from French optique or medieval Latin opticus, from Greek optikos, from optos ‘seen.’

optic (op-tik) adj. concerned with the eye or vision. o. atrophy degeneration of the optic nerve. o. chiasm (o. commissure) the X-shaped structure formed by the two optic nerves as nerve fibres from the nasal side of the retina of each eye cross over to join fibres from the lateral side of the retina of the opposite eye (see illustration). o. disc (o. papilla) the start of the optic nerve, where nerve fibres from the rods and cones leave the eyeball. See blind spot. o. nerve the second cranial nerve (II), which is responsible for vision. It passes into the skull behind the eyeball to reach the optic chiasm, after which the visual pathway continues to the occipital lobe. o. neuritis see retrobulbar neuritis.

optic pert. to sight or the organ of sight. XVI. — (O)F. optique or medL. opticus — Gr. optikós, f. optós seen, visible, f. *op-; see EYE, -IC.
So optical, optics XVI.

optic Dispenser attached to bottles of spirits, etc., in bars to ensure delivery of a precise volume.