1. 
   dioptrical
   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. ... <geometry> ' Dioptric curve, a Cartesian oval. See Cartesian. ... Origin: Gr. Belonging to the use of the; = thro...
   Found op http://www.mondofacto.com/facts/dictionary?dioptrical
   
   
2. 
   Dioptrical
   • (a.) Of or pertaining to dioptrics; assisting vision by means of the refraction of light; refractive; as, the dioptric system; a dioptric glass or telescope.
   Found op http://thinkexist.com/dictionary/meaning/dioptrical/
   
   

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