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The Collaborative International Dictionary
Dioptric curve

Dioptric \Di*op"tric\, Dioptrical \Di*op"tric*al\, a. [Gr. ? belonging to the use of the ?; ? = dia` through + the root of ? 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.

Dioptric curve (Geom.), a Cartesian oval. See under Cartesian.