noun
1.
a. : a straight line perpendicular to the front of the cornea of the eye and extending through the center of the pupil
b. : the axis of symmetry of a radially symmetrical optical system
2. : optic axis 1
noun
1.
a. : a straight line perpendicular to the front of the cornea of the eye and extending through the center of the pupil
b. : the axis of symmetry of a radially symmetrical optical system
2. : optic axis 1
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012