a. (Optics) Of or pertaining to the dioptre, or to the metric system of numbering glasses. -- n. A dioptre. See Dioptre.

{ } a. [ Gr. &unr_; belonging to the use of the &unr_;; &unr_; = dia` through + the root of &unr_; I shall see: cf. F. dioptrique. ] Of or pertaining to dioptrics; assisting vision by means of the refraction of light; refractive; as, the dioptric system; a dioptric glass or telescope. “Dioptrical principles.” Nichol. [ 1913 Webster ]

Dioptric curve (Geom.), a Cartesian oval. See under Cartesian. [ 1913 Webster ]

n. [ Gr. &unr_; &unr_;: cf. F. dioptrique. ] (Optics) The science of the refraction of light; that part of geometrical optics which treats of the laws of the refraction of light in passing from one medium into another, or through different mediums, as air, water, or glass, and esp. through different lenses; -- distinguished from catoptrics, which refers to reflected light. [ 1913 Webster ]