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

Reducing or randomizing the polarization of an electromagnetic wave, by transmission through a non-homogeneous medium or a depolarizer.

from → de- + → polarization.

The action of deporting an alien from a country.

→ deport; → -tion.

The process by which water vapor changes directly to ice without first becoming a liquid. This is how snow forms in clouds, as well as frost and hoar frost on the ground. The opposite of deposition is → sublimation. → condensation.

M.E., from O.Fr. deposition, from L. deposition- "putting aside, testimony, burial," from deposit(us) "laid down," p.p. of deponere "to put down," from → de- + ponere "to put, place."

Vâneheš, from vâ-→ de- + neheš verbal noun of nehâdan "to put, place," Mid.Pers. nihâtan, O.Pers./Av. ni- "down; into," → ni-, + dā- "to put; to establish; to give," dadāiti "he gives," cf. Skt. dadâti "he gives," Gk. didomi "I give," L. do "I give;" PIE base *do- "to give."

An act of attacking or plundering.

→ de-; → predation.

1) Navigation:→ dip.
2) Meteorology: An area of low atmospheric pressure.
3) Geology: An area of the Earth's crust sunken or depressed below the surrounding area, formed by various mechanisms.

Depression, verbal noun of depress, from O.Fr. depresser, from L.L. depressare, frequentative of pressus, p.p. of deprimere "press down," from → de- "down" + premere "to press."

1) Našib-e ofoq, from našib "declivity, descent; lowness of ground, slope of any place" (Mid.Pers. nišēp "declivity, (astrology) dejection," Av. *nixšvaēpā-, xšvaēpā- "bottom, rear") + ofoq→ horizon. 2) Forubâr, from foru "down, downward; below; beneath," → de- + bâr "load, pressure, charge," → charge. 3) Našiblâx, from našib, as above, in item 1, + -lâx place suffix.

1) General: The act or fact of deriving or being derived; origin; descent.
2) Math.:→ differentiation; development of a theorem.
3) Grammar: The formation of a word from another word or base. It typically occurs by the addition of an affix.

Verbal noun of → derive.

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.

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 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.

The act or state of detecting, → detect
Any operation on an electrical or electromagnetic signal to recover information from it.

M.E., from L.L. detection-, from detect(us), → detect, + -ion.

škâreš, from âškâr present-tense stem of âškâridan→ detect + -š verbal noun suffix.

The act of deciding definitely and firmly; the result of such an act of decision.

Verbal noun of → determine.

Instantaneous combustion or conversion of a solid, liquid, or gas into larger quantities of expanding gases accompanied by heat, shock, and a noise. → deflagration; → explosion.

Verbal noun of → detonate.

The process of introducing → deuterium into a → chemical compound.

Verbal noun of → deuterate.

The difference between the deuterium (D)/hydrogen (H) → abundance → ratio in an object with respect to that representing a standard or mean value for that type of objects. Same as → isotope fractionation of deuterium. In the gas phase chemistry many of the D fractionation reactions produce an excess of D atoms relative to → hydrogen atoms. Deuterium fractionation in → interstellar cloud cores, → protostars, and → Solar System bodies is frequently used to infer important aspects of their physical and chemical histories. For example, the → deuterium enhancement in the Earth's sea water, with respect to the cosmic abundance, has been interpreted as being due to → enrichment by → comet-like → planetesimals colliding with the young Earth.

→ deuterium; → fractionation.

The act of deviating; departure from a standard or norm.
Statistics: The difference between a datum and some reference value, typically the mean of the data. → standard deviation.

Verbal noun form of → deviate.

1) Profound dedication; consecration.
2) Earnest attachment to a cause, person, etc. (Dictionary.com).

Verbal noun of → devote.

The clockwise rotation of the → plane of polarization of light (as viewed by an observer looking straight in the incoming light) by certain substances. See also → levorotation.

→ dextro-; → rotation.

A reference source in print or electronic form containing words alphabetically arranged along with information about their forms, meanings, pronunciations, etymologies, etc.

M.L. dictionarium "collection of words and phrases," from L. dictionarius "of words," from dictio "word" from dic-, p.p. stem of L. dicere "speak, tell, say," from PIE root *deik- "to point out;" cf. Av. daēs- "to show," daēsa- "sign, omen;" cf. Skt. deś- "to show, point out;" → form.

Farhang, → culture.

An → equation of state for → real gases which leads to the → van der Waals equation as a → first approximation. It is of the form P(V - b) [exp (a/VRT)] = RT, where P is the pressure, V is the volume, T is the thermodynamic temperature, R is the → gas constant, and a and b are the constants characteristic of the gas.

Named after Conrad Dieterici (1858-1929), a German physicist; → equation.

Property of a mathematical function if it has a → derivative at a given point.

From → differentiable; → function.