Optic

a. [Fr. optique, Pr. optic, Sp. & Pg. optico, It. ottico, Gr. ὀπτικός, from the root ὄπ, future ὄψομαι, to see.] 1. Relating or pertaining to vision or sight. The moon, whose orb, Through optic glass, the Tuscan artist views. Milton.

2. Relating or pertaining to the organ of sight; as, the optic nerve.
3. Relating to the science of optics; as, optical works.

Optic angle, the angle included between the two lines drawn from the two extreme points of an object to the center of the pupil of the eye; the visual angle;—sometimes, also, employed as equivalent to binocular parallax;—called also visual angle. Hutton.—Optic axis. (a.) A line drawn through the center of the eye perpendicular to its anterior and posterior surfaces. (b.) The line in a double refracting crystal, in the direction of which no double refraction occurs.—Optical square, a surveyor's instrument for laying out perpendicular lines. Simmonds.