dioptre

Noun
Synonyms: diopter

WordNet 3.0

Noun (1)

  1. a unit of measurement of the refractive power of a lens which is equal to the reciprocal of the focal length measured in meters; used by oculistsSynonyms: diopter
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Webster's Dictionary (GCIDE)

Dioptre \Di*op"tre\, n. [F. See 2d Dioptric.] (Optics) A unit employed by oculists in numbering glasses according to the metric system; a refractive power equal to that of a glass whose principal focal distance is one meter. [1913 Webster]
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