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Webster 1913 Edition

Noun.

(Opt.)

That part of optics which treats of the refraction of light; – commonly called dioptrics.

Encyc. Brit.

Noun.

That part of optics which treats of the refraction of light, commonly called dioptrics, which see.

anaclastics ‎(uncountable)

The part of optics that deals with the refraction of light.
(Can we find and add a quotation of Encyc. Brit to this entry?)