An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) General: Derived from another; not original or primitive.
2) Math.: For a → function  y = f(x), the → limit of the → ratio of the → increment of the function, Δy, to the increment of the → variable, Δx, as the latter tends to → zero. Derived function; result of → differentiation.
3) Chemistry: Substance derived or prepared from some other → substance.

From M.E. derivatif, from L.L. derivativus, from derivat(us), p.p. of derivare, → derive + -ivus.

Vâxané, noun from vâxan, present stem of vâxanidan, → derive.

1) General: To conduct, draw, obtain from a source or origin; to trace to an origin.
2) Chemistry: To produce or obtain (a → substance) from another.
3) Math.: Verbal form of → derivation.

From O.Fr. dériver, from L. derivare "to draw off (a stream of water), from its source," from de- "from" + riv(us) "a stream" + -are infinitive suffix.

Vâxanidan, from vâ- prefix which indicates "returning to, reference," → de-, + xan "source," variant xân (Gilaki xoni, Tabari xoni, Laki kyani, Tâleši xâni, xoni, Mid.Pers. xân, xânig "source, spring," Av. xā-, xan- "source, fountain, spring," xayana- "belonging to a spring," cf. Khotanese khâhâ- "spring, fountain," Skt. khâ'- "spring, source") + -idan infinitive suffix.

Determined by mathematical computation; formed or developed from something else; not original.

P.p. of → derive.

René Descartes (1596-1650), French mathematician, physicist, and philosopher, who made valuable contributions to mathematics, physics, and philosophy. Descartes was a pioneer and major figure in 17th century rationalism. He represents a major break with the Aristotelianism and Scholasticism of the Medieval period. René Descartes is regarded as the father of modern philosophy. → Descartes ray, → Cartesian coordinates, → Cartesian vortex theory.

Same as → rainbow ray.

→ Descartes; → ray.

A formula that gives the position of an image formed by highly → paraxial rays from a → spherical mirror. It is quite accurately given by: 1/x_o + 1/x_i = 2/x_C, where x_o is the distance along the → principal axis from the mirror to the object, x_i is the distance from mirror to image, and x_C is the distance from the mirror to its center of curvature. Any distance measured on the same side of the mirror as the reflecting surface is positive; on the other side, negative. Thus for a → concave mirror  x_C is positive; for a → convex mirror, negative.

→ Descartes; → formula.

1) To go or pass from a higher to a lower place.
2) To be passed on by parents or ancestors; be inherited

M.E. descenden, "move or pass from a higher to a lower place," from O.Fr. descendre "descend, dismount; fall into; originate in," from Latin descendere "come down, descend, sink," from → de- "down" + scandere "to climb," from PIE root *skand- "to spring, leap, climb."

1) A person, animal, or plant that is descended from a specific individual, race, species, etc.
2) Something deriving in appearance, function, or general character from an earlier form.

→ descend.

The point in an → orbit where the orbiting body crosses a reference plane, such as the → ecliptic or the → celestial equator, going from north to south. → ascending node.

→ descend; → -ing; → node.

1) General: To tell or represent in written or spoken words; give an account of.
2) Geometry: To draw or trace the outline of.

M.E. describen, from L. describere, from → de- + scribere "to write," from PIE *skreibh- (cf. Gk. skariphasthai "to scratch an outline, sketch;" Lett. skripat "scratch, write;" O.N. hrifa "scratch"); PIE base *sker- "cut, incise."

Vâveštan, vâvisidan (on the model of neveštan, nevisidan "to write"), from vâ-, → de-, + vešt-, vis-, → inscribe.

1) The act or method of describing.
2) A statement, picture in words, or account that describes.
3) Geometry: The act or process of describing a figure.

Verbal noun of → describe.

Serving to describe; containing description.

→ describe; → -ive.

1) An arid land where average annual precipitation is so low (usually taken as below 250 mm mean annual rainfall) that it will not adequately support vegetation, and where the potential rate of evaporation far exceeds precipitation.
2) Any place lacking in something; → brown dwarf desert.

From M.E., from O.Fr. desert, from L.L. desertum, literally "thing abandoned," from deserere "to abandon."

Kavir "salt and sour ground, where nothing grows; wilderness," of unknown origin.

1a) An outline, sketch, or plan, as of the form and structure of a work of art, an edifice, or a machine to be executed or constructed.
1b) Organization or structure of formal elements in a work of art; composition.
2a) To prepare the preliminary sketch or the plans for (a work to be executed), especially to plan the form and structure of.
2b) To plan and fashion artistically or skillfully.
2c) To intend for a definite purpose (Dictionary.com).

M.E. designen, from M.Fr. desseign "purpose, project, design," from It. disegno, from disegnare "to mark out," from L. designare "mark out, devise, designate, appoint," from → de- "out" + signare "to mark," from signum "a mark, → sign."

Barsé, related to (Delijâni) barsi "to throw," variants baysi, vaesi, deresi; (Xonji, Gerâši) bar-, barressa "to fall down;" ultimately from Proto-Ir. *garH- "to throw;" cf. (+*ni-) Av. niγr- "to throw down;" Khotanese bīr- "to throw, sow;" Pers. garzin "a pointed arrow;" Pashto qoer "jump, leap," aqar "fitting an arrow to the bow-string ready to shoot;" cf. Skt. gar- "to raise a weapon;" Gk. ballein "to throw," → problem, blema "projectile;" PIE root *g^welH- "to throw" (Cheung 2007). Barsé is coined on the model of Ger. Entwurf "design; project" and entwerfen "to design," from werfen "to throw;" Pers. dar-andâxtan "to propound, to pose" (Hâfez: falak râ saxt beškâfim o tarhi now dar-andâzim); also Ar. tarh (طرح) "to throw."

A distinctive name or title; appellation. → Bayer designation; → Flamsteed designation; → variable star designation.

From L. designatus, p.p. of designare "to mark out, choose, appoint," from → de- "out" + signare "to mark," from signum, → sign.

Nâmgozini, from nâm, → name, + gozini "choosing," from gozidan "to chose," → select.

A person who devises or executes designs, especially one who creates forms, structures, and patterns, as for works of art or machines (Dictionary.com).

→ design; → -er.

Verbal form of → desorption.

Desorb, from → de- + -sorb, modeled on → absorb.

vâšamidan, from vâ-, → de-, + šamidan, modeled on baršamidan, → absorb.

A physical or chemical process by which a substance that has been sorbed (adsorbed or absorbed) by a liquid or solid material is removed from the material. Reverse of → sorption. → absorption; → adsorption.

Verbal noun of → desorb.

In spite of; notwithstanding.

M.E. despit, from O.Fr. despit, from L. despectus "a looking down on, scorn, contempt," from p.p. of despicere "to look down on, scorn," from → de- "down" + spicere/specere "to look at," → scope; the preposition is contraction of in despite of, a loan-translation of O.Fr. en despit de "in contempt of."

Pâdkâm, literally "against (one's) will or desire," from pâd- "against, contrary," → anti-, + kâm "desire, wish;" Mid.Pers. kâm "desire, wish;" cf. Skt. kāma- "desire, wish."

An → interference process in which the → amplitude of the the amplitude of the resultant wave is less than that of either individual waves. See also → constructive interference.

Destructive, from O.Fr. destructif, from L.L. destructivus, from destruct-, p.p. stem of destruere, from → de- + struere "to build," → structure; → interference.

Andarzaneš, → interference; virângar "destructive," from virân, "destroyed, ruined."