An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1054
Purkinje effect
  ا ُسکر ِ پورکین‌ی   
oskar-e Purkinje

Fr.: effect Purkinje   

The increasing sensibility of the retina for light of shorter wavelength as the brightness decreases. In those conditions red objects are perceived to fade faster than blue objects of the same brightness.

Named after the Czech anatomist Jan Evangelista Purkynne (1787-1869), who discovered the effect; → effect.


Fr.: but, objet   

The reason for which something exists or is done, made, used, etc. (

M.E. purpos, from O.Fr. porpos "aim, intention," from porposer "to put forth," from por- "forth," from L. → pro- "forth;" + O.Fr. poser "to put, place," → position.

Farneh, literally "put forth," from far-, variant of farâ-, → pro-, + neh present stem of nehâdan "to pose, place, lay," → position.


Fr.: résolu, déterminé   

Having a purpose; determined; resolute.

purpose + -ful a suffix meaning "full of," "characterized by."

Farnehmand, from farneh, → purpose, + -mand, → -al.


Fr.: exprès   

1) Intentionally; deliberately.
2) With the particular purpose specified; expressly (

purpose; → -ly.

cistân (#)

Fr.: énigme   

1) A problem that cannot be easily or readily solved.
2) A game, question, or problem designed for testing ingenuity.

Of unknown origin.

Cistân from cist "what is?," + -ân noun suffix.

pycnonuclear reaction
  واژیرش ِ چگال‌هسته‌ای   
vâžireš-e cagâl-hasteyi

Fr.: réaction pycnonucléaire   

A nuclear reaction that takes place at high densities and relatively low temperatures. Pycnonuclear reactions are almost temperature independent and occur even at zero temperature. These reactions are extremely slow at densities typical for normal stars but intensify with increasing density. For example, carbon burns into heavier elements at densities over 1010 g cm-3.

Pycnonuclear, from pycno- a combining form meaning "dense, thick," from Gk. pyknos "dense, solid" + → nuclear; → reaction.

Vâžireš, → reaction; cagâl-hasteyi, from cagâl, → dense, + hasteyi, → nuclear.


Fr.: pyrhéliomètre   

General term for the class of → actinometers that measure the intensity of solar radiation received on the surface of the Earth. It functions by converting the heat of the sunlight into a voltage using a device called a thermopile, and a recording voltmeter.

From pyr-, from → pyro- + → heliometer.

pirit (#)

Fr.: pyrite   

A yellow → mineral which is an iron sulfide (FeS2). It is a source of → sulfur and is used in the manufacture of sulfuric acid.

M.E., from O.Fr. pirite, from L. pyrites, from Gk. pyr "fire," → pyro-, + → -ite.


Fr.: pyro-   

A prefix meaning "fire, heat, high temperature," used in the formation of compound words. → pyrheliometer; → pyrometer.

From Gk. pyro-, combining form of pyr "fire," cognate with O.E. fyr, O.N. fürr, M.Du. vuur, Ger. Feuer), from PIE *paewr-; cf. Mod.Pers. Lori porpor "blazing charcoal," Gilaki bur, biur "smokeless red fire" (Lori perisk, periska "spark," Kurd. biriske "spark," Lârestâni pelita "spark"); Gk. pyr "fire;" Hitt. pahhur "fire;" Skt. pū- "to cleanse."

&ACIRC;zar, variants âtaš, taš "fire," from Mid.Pers. âtaxš, âtur "fire;" Av. ātar-, āθr- "fire," singular nominative ātarš-; O.Pers. ātar- "fire;" Av. āθaurvan- "fire priest;" Skt. átharvan- "fire priest;" cf. L. ater "black" ("blackened by fire"); Arm. airem "burns;" Serb. vatra "fire;" PIE base *āter- "fire."

âzarsanj (#)

Fr.: pyromètre   

A device used for measuring high temperatures. By comparing a source whose temperature is to be measured to a standardized source of illumination, it determines the temperature of the former source.

pyro- + → -meter.

piroksen (#)

Fr.: pyroxène   

One of the major groups of silicate minerals found in many igneous and metamorphic rocks. Pyroxene minerals are also common in meteorites. There are many different types of pyroxene. All of the types contain Si2O6 but some have sodium (Na) while others have iron (Fe), magnesium (Mg), or a combination of these three elements.

From → pyro- "fire," + xeno- a combining form meaning "alien, strange, guest," from Gk. xenos "stranger, guest." Pyroxene was originally supposed to be a foreign substance when found in igneous rocks.

Pythagorean theorem
  فربین ِ پوتاگوراس، ~ فیساغورس   
farbin-e Pythagoras, ~ Fisâqures

Fr.: théorème de Pythagore   

The proposition that the → square of the → hypotenuse of a → right triangle is equal to the → sum of the squares of the other two sides: a2 + b2 = c2.

After Pythagoras (c570 BC-c495BC), Greek philosopher and mathematician; → theorem.

Pythagorean triple
  سه‌تایه‌ی ِ پوتاگوراس، ~ فیساغورس   
setâye-ye Pythagoras, ~ Fisâqures

Fr.: triplet de Phythagore   

Any group of three → integers that satisfy the relations specified by the → Pythagorean theorem. Some examples: 3, 4, and 5; 5, 12, and 13; 8, 15, 17.

Pythagorean theorem; → triple; → triplet.

qotb-namâ (#)

Fr.: Boussole   

The Compass Box. A faint constellation in the southern hemisphere, at 9h right ascension, 30° south declination, representing a mariner's compass. Its brightest star, Alpha Pyxidis, is magnitude 3.7. Abbreviation: Pyx; genitive: Pyxidis.

L. pyxis, from Gk. pyxis "box."

Qotbnamâ literally "pole indicator," from qotb, → pole, + namâ "displayer, indicator," from nemudan "to show" (Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into" (Skt. ni "down," nitaram "downward," Gk. neiothen "from below," cf. E. nether, O.E. niþera, neoþera "down, downward, below, beneath," from P.Gmc. *nitheraz, Du. neder, Ger. nieder; PIE *ni- "down, below") + māy- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure").

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