Search Result for "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 oculists;
[syn: diopter, dioptre]



The Collaborative International Dictionary of English v.0.48:

Diopter \Di*op"ter\, Dioptra \Di*op"tra\, n. [L. dioptra, fr.
   Gr. ?. See 2d Dioptric.]
   An optical instrument, invented by Hipparchus, for taking
   altitudes, leveling, etc.
   [1913 Webster]


WordNet (r) 3.0 (2006):

diopter
    n 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 oculists [syn: diopter,
         dioptre]