An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 699

Fr.: démontrer   

1) To make evident or establish by arguments or reasoning; prove.
2) To describe, explain, or illustrate by examples, specimens, experiments, or the like.
3) To manifest or exhibit; show.
4) T display openly or publicly, as feelings (

From L. demonstratus, p.p. of demonstrare "to show, point out," from → de- + monstrare "to show," from monstrum "sign, portent."

Padišidan, from Sogd. padēš "to show," ultimately from Proto-Ir. *apa-dais-, from *dais- "to show," cf. Av. daēs- "to show," related to andiš, → think.

  پدیش، پدیشش   
padiš, padišeš

Fr.: démonstration   

1) The → act or → circumstance of proving or being → proved conclusively, as by → reasoning or a show of → evidence.
2) Something serving as → proof or supporting evidence.
3) An exhibition, as of feeling; display; → manifestation (

Verbal noun of → demonstrate.


Fr.: démonstrateur   

A person or thing that demonstrates (

demonstrate; → -or.


Fr.: démystification   

The removal of mystery or confusion surrounding a topic or idea.

demystify; → -tion.


Fr.: démystifier   

To rid of mystery or obscurity; clarify. The removal of mystery or confusion surrounding a topic or idea.

de-; → mystify;


Fr.: dendrite   

1) A branching treelike figure produced on or in a mineral by a foreign mineral.
2) A crystallized → arborescent form.
3) Any of the usually branching protoplasmic processes that conduct impulses toward the body of a neuron (

From Gk. dendrites "of or pertaining to a tree," from dendron "tree," cognate with Pers. deraxt, variant dâr, → tree.

Šâxzâré, from šâxzâr, from šâxsâr "full of branches," from šâx, šâxé, → branch, + suffix -zâr denoting profusion, and abundance, as in kârzâr "a field of battle; combat" šurezâr "unfertile, salty ground; nitrous earth," xoškzâr "arid land," and so forth.

dâršenâsi (#)

Fr.: dendrologie   

The branch of → botany dealing with trees and shrubs. Dendrology studies the distinguishing characteristics of tree species for the purpose of identification and classification into orders and other natural groups.

From dendro- a combining form meaning "tree," from Gk. dendron "tree," related to Pers. dâr, → tree, + → -logy.

Deneb (α Cygni)
Zanab (#)

Fr.: Deneb   

The brightest star, of magnitude V = 1.25, in the constellation → Cygnus. It is a → supergiant of → spectral type A2 Ia.

Deneb "tail," from Ar. dhanab ad-dajajah (ذنب الدجاجه) "tail of the hen," referring to the legendary swan (Cygnus) in Gk. mythology.

Zanab, from Ar., as above.

Denebola (β Leonis)
  شیردم، ذنب الاسد   
Širdom, Zanab-ol-asad (#)

Fr.: Denebola   

The second brightest star, of magnitude V = 2.14, in the constellation → Leo. A → main sequence star of → spectral type A3 V.

Denebola, from Ar. dhanab al-asad (ذنب الاسد) "tail of the lion," referring to the lion in Gk. mythology.

Širdom "tail of the lion," from šir "lion" → Leo + dom "tail," → comet. Zanab-ol-asad from Ar., as above.


Fr.: dénégation, démenti   

1) An assertion that something said, believed, alleged, etc., is false.
2) Refusal to believe a doctrine, theory, or the like.
3) Disbelief in the existence or reality of a thing (

deny; → -al.


Fr.: dénominateur   

The quantity y in a fraction x/y. The quantity x is the → numerator.

M.L. denominator, from denomina(re), from → de- + nominare "to name, call by name," from nomen "name," cognate with Pers. nâm "name," as below.

Nâmân, adj./agent noun of nâmidan "to name," from nâm "name;" Mid.Pers. nâm; O.Pers./Av. nâman-; cf. Skt. nama-; Gk. onoma, onuma; L. nomen; PIE *nomen-.


Fr.: dénoncer   

1) To condemn or censure openly or publicly.
2) To make a formal accusation against, as to the police or in a court (

de-; → announce.

cagâl (#)

Fr.: dense   

Having relatively high → density.
Math.: The quality of a subset A of a topological space X, indicating that any point in X can be well approximated by points in A.

From L. densus "thick, crowded," cognate with Gk. dasys "hairy, bushy, thick grown."

Cagâl "dense, thick," related to ceqer "stiff, hard, tough, firm" (dialectal Kermâni ceqel, Šândizi caqal), caqâlé "stiff, unripe fruit."

dense core
  مغزه‌ی ِ چگال   
maqze-ye xagâl

Fr.: coeur dense   

An opaque region of a → molecular cloud (AV  10 mag) which is considered to be the progenitor of → star formation. Dense cores have temperatures of about 10 K and masses of roughly 1 to 10Msun each and in which the → molecular hydrogen density is roughly 104-105 cm-3 and size 0.1 pc. The → self-gravity of a dense core plays a central part in star formation. See also → hot molecular core.

dense; → core.

dense core mass function
  کریای ِ جرم ِ مغزه‌ی ِ چگال   
karyâ-ye jerm-e maqze-ye cagâl

Fr.: fonction de masse des cœurs denses   

core mass function.

dense; → core; → mass; → function.

dense molecular cloud
  ابر ِ مولکولی ِ چگال   
abr-e molekuli-ye cagâl

Fr.: nuage moléculaire dense   

A type of → interstellar medium cloud in which → carbon (C) becomes almost completely molecular due to relatively high → extinction. The chemistry is qualitatively different from that of → diffuse molecular clouds, as the → electron abundance is very low (→ cosmic-ray ionization being the dominant source) and the reactive C is replaced by the very stable → carbon monoxide (CO). This regime is found only in → sightlines with AV > 5-10 mag; not all such sightlines will contain dense cloud material and if dense cloud material is present it is likely to be surrounded by → translucent material. These clouds are typically → self-gravitating, and are most often observed by → infrared absorption and → millimeter wave emission methods. Their densities are typically at least 104 cm-3, and their → kinetic temperatures are typically on the order of 10-50 K in the quiescent regions. Most of the more than 140 currently known → interstellar molecules were found through observations of → microwaverotational transitions in such clouds, starting with the discovery of OH, followed by a host of other new detections such as CO, NH3, H2O, and H2CO (Snow & McCall, 2006, ARA&A 44, 367).

dense; → molecular; → cloud.

cagâli (#)

Fr.: densité   

The amount of any quantity per unit volume. The mass density is the mass per unit volume. The energy density is the energy per unit volume; particle density is the number of particles per unit volume.
See also:
charge density, → column density, → critical density, → current density, → density fluctuation, → density parameter, → density profile, → density wave, → density-bounded H II region, → density-wave theory, → electron density, → energy density, → flux density, → magnetic flux density, → maximum density of water, → neutral density filter, → nuclear density, → number density, → optical density, → period-mean density relation, → Planck density, → potential density, → power spectral density, → probability density function, → radio flux density, → relative density, → specific density, → spectral density, → surface density.

Noun form of → dense.

density fluctuation
  افتاخیز ِ چگالی   
oftâxizhâ-ye cagâli

Fr.: fluctuations de densité   

In the early Universe, localized enhancements in the density of either matter alone or matter and radiation. According to models, very small initial fluctuations (less than 1 percent) can lead to subsequent formation of galaxies.

density; → fluctuation.

density parameter
  پارامون ِ چگالی   
pârâmun-e cagâli

Fr.: paramètre de densité   

One of the four terms that describe an arranged version of the → Friedmann equations. They are all time dependent.
1) For matter: Ωm = 8πGρm/(3H2), where G is the → gravitational constant, ρm is the mean matter density, and H the → Hubble parameter. The matter density parameter is also expressed as Ωm = ρmcrit, where ρcrit is the → critical density.
2) For radiation: Ωr = 8πGρr/(3H2), where ρr is the radiation equivalent of matter density. This parameter is also expressed as Ωr = ρrcrit.
3) For the → cosmological constant: ΩΛ = Λc2/(3H2). Similarly, ΩΛ = ρΛcrit, where &rhoΛ = Λc2/(8πG) is sometimes referred to as the density of → dark energy.
4) For the → curvature of space-timeΩk = -kc2/(R2H2), where k is the → curvature constant and R the → cosmic scale factor.
Note that: Ωm + Ωr + ΩΛ + Ωk = 1, and Ωtotal = Ωm + Ωr + ΩΛ = 1 - Ωk.

density; → parameter.

density profile
  فراپال ِ چگالی   
farâpâl-e cagâli

Fr.: profile de densité   

1) A → profile representing the → density of a quantity.
2) A → profile representing the distribution of stars as a function of their number in a region.

density; → profile.

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