dioptrical

Di*op"tric, Di*op"tric*al, a. Etym: [Gr. dioptrique.] Defn: 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. Dioptric curve (Geom.), a Cartesian oval. See under Cartesian.

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