diopter Meaning, Definition & Usage

  1. noun 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 oculists
    dioptre.

WordNet

Di*op"ter, Di*op"tra noun (Also<
  • Diopter
  • Dioptra
)
Etymology
L. dioptra, fr. Gr. . See 2d Dioptric.
Definitions
  1. An optical instrument, invented by Hipparchus, for taking altitudes, leveling, etc.

Webster 1913