Di"o*dont (?), a. (Zoöl.) Like or pertaining to the genus Diodon. -- n. A fish of the genus Diodon, or an allied genus.
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||Di*"ci*a (d*"sh*), n. pl. [NL., fr. Gr. di = di`s twice + o'i^kos a house.] 1. (Bot.) A Linnæan class of plants having the stamens and pistils on different plants.
2. (Zoöl.) A subclass of gastropod mollusks in which the sexes are separate. It includes most of the large marine species, like the conchs, cones, and cowries.
{ Di*"cian (?), Di*"cious (?), } a. (Biol.) Having the sexes in two separate individuals; -- applied to plants in which the female flowers occur on one individual and the male flowers on another of the same species, and to animals in which the ovum is produced by one individual and the sperm cell by another; -- opposed to moncious.
Di*"cious*ly, adv. (Biol.) In a dicious manner.
Diciously hermaphrodite (Bot.), having flowers structurally perfect, but practically dicious, -- those on one plant producing no pollen, and those on another no ovules.
Di*"cious*ness, n. (Biol.) The state or quality of being dicious.
Di*"cism (?), n. (Biol.) The condition of being dicious.
Di*og"e*nes (?), n. A Greek Cynic philosopher (412?-323 B. C.) who lived much in Athens and was distinguished for contempt of the common aims and conditions of life, and for sharp, caustic sayings.
Diogenes' crab (Zoöl.), a species of terrestrial hermit crabs (Cenobita Diogenes), abundant in the West Indies and often destructive to crops. -- Diogenes' tub, the tub which the philosopher Diogenes is said to have carried about with him as his house, in which he lived.
Di*oi"cous (?), a. See Dicious.
||Di*om`e*de"a (?), n. [NL.] (Zoöl.) A genus of large sea birds, including the albatross. See Albatross.
||Di`o*næ"a (?), n. [NL., fr. Gr. &?; a name of Aphrodite.] (Bot.) An insectivorous plant. See Venus's flytrap.
Di`o*ny"sian (?), a. Relating to Dionysius, a monk of the 6th century; as, the Dionysian, or Christian, era.
Dionysian period, a period of 532 years, depending on the cycle of the sun, or 28 years, and the cycle of the moon, or 19 years; -- sometimes called the Greek paschal cycle, or Victorian period.
Di`o*phan"tine (?), a. Originated or taught by Diophantus, the Greek writer on algebra.
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.
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.
Di*op"tase (?), n. [Gr. &?; = dia` through + &?; to see: cf. F. dioptase.] (Min.) A hydrous silicate of copper, occurring in emerald-green crystals.
{ 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.
||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.
Di*op"tric (?), a. (Optics) Of or pertaining to the dioptre, or to the metric system of numbering glasses. -- n. A dioptre. See Dioptre.
{ 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.
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.
Di*op"try (?), n. (Optics) A dioptre.
Di`o*ra"ma (?), n. [Gr. &?; to see through; &?; = dia` through + &?; to see; cf. &?; that which is seen, a sight: cf. F. diorama. Cf. Panorama.] 1. A mode of scenic representation, invented by Daguerre and Bouton, in which a painting is seen from a distance through a large opening. By a combination of transparent and opaque painting, and of transmitted and reflected light, and by contrivances such as screens and shutters, much diversity of scenic effect is produced.