Chapter Dimplement to Dioptry of D by Webster's Dictionary (1913 Edition)

Diophantine analysis

(Alg.), that branch of indeterminate analysis which has for its object the discovery of rational values that satisfy given equations containing squares or cubes; as, for example, to find values of x and y which make x² + y² an exact square.

Diopside
(Di*op"side) n. [Gr. di- = di`s- twice + a sight, fr. the root of I shall see: cf. F. diopside.] (Min.) A crystallized variety of pyroxene, of a clear, grayish green color; mussite.

Dioptase
(Di*op"tase) n. [Gr. = dia` through + to see: cf. F. dioptase.] (Min.) A hydrous silicate of copper, occurring in emerald-green crystals.

Diopter
(Di*op"ter ||Di*op"tra) n. [L. dioptra, fr. Gr. . See 2d Dioptric.] An optical instrument, invented by Hipparchus, for taking altitudes, leveling, etc.

Dioptre
(||Di*op"tre) n. [F. See 2d Dioptric.] (Optics) 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.

Dioptric
(Di*op"tric) a. (Optics) Of or pertaining to the dioptre, or to the metric system of numbering glasses. — n. A dioptre. See Dioptre.

Dioptric
(Di*op"tric Di*op"tric*al) a. [Gr. belonging to the use of the = dia` through + the root of I shall see: cf. F. dioptrique.] Of or pertaining to dioptrics; assisting vision by means of the refraction of light; refractive; as, the dioptric system; a dioptric glass or telescope. "Dioptrical principles." Nichol.

Dioptric curve (Geom.), a Cartesian oval. See under Cartesian.

Dioptrics
(Di*op"trics) n. [Gr. : cf. F. dioptrique.] (Optics) The science of the refraction of light; that part of geometrical optics which treats of the laws of the refraction of light in passing from one medium into another, or through different mediums, as air, water, or glass, and esp. through different lenses; — distinguished from catoptrics, which refers to reflected light.

Dioptry
(Di*op"try) n. (Optics) A dioptre.