diopter

2 definitions found

diopter - 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]

diopter - WordNet (r) 2.1 (2005) :

  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]