Diopter

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  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]



From WordNet (r) 2.0 [wn]:

  diopter
       n : a unit of measurement of the refractive power of a lens
           which is equal to the reciprocal of the focal length
           measured in meters