dioptre
Di*op"tre, n. Etym: [F. See 2d Dioptric.] (Optics) Defn: 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.
Di*op"tre, n. Etym: [F. See 2d Dioptric.] (Optics) Defn: 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.