An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 1076

Fr.: permettre   

To allow to be done or occur.

From M.Fr. permetre, from L. permittere "give up, allow, allow to pass through," from per- "through;" (from PIE base *per- "through, across, beyond;" cf. Gk. peri "around, about, beyond;" O.Pers. pariy "around, about," Av. pairi "around, over;" Skt. pari; Indo-Iranian *pari- "around;" Mod.Pers. par-, pirâ- "around, about") + mittere "let go, send."

Parzâmidan, literally "to allow to go through," infinitive of parzâm, from par- "through," from O.Pers. pariy "around, about," Av. pairi "around, over," cognet with L. per-, as above + zâm stem of Mid.Pers. zâmenidan "to let go, lead, send," Mod.Pers. gâm "step, pace," âmadan "to come;" O.Pers./Av. gam- "to come; to go," Av. jamaiti "goes;" cf. Skt. gamati "goes;" Gk. bainein "to go, walk, step," L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come," E. come; PIE base *gwem- "to go, come."


Fr.: permis   

Allowed. → permitted line; → permitted transition.

Past participle of → permit.

permitted line
  خط ِ پرزامیده   
xatt-e parzâmidé

Fr.: raie permise   

An ordinary spectral line emitted by atoms undergoing energy transitions that are allowed by the selection rules of quantum mechanics. → forbidden lines.

permitted; → line.

permitted transition
  گذرش ِ پرزامیده   
gozareš-e parzâmidé

Fr.: transition permise   

A transition between two quantum mechanical states that does not violate the quantum mechanical selection rules.

permitted; → transition.


Fr.: permittivité   

A measure of the ability of a material to transmit (or "permit") an electric field. Permittivity is defined as the ratio of the flux density produced by an electric field in a given dielectric to the flux density produced by that field in a vacuum. In → SI units, permittivity is measured in → farads per meter. The constant ε0 is known as the permittivity of free space; its value is about 8.854 x 10-12 F/m.

State or quality noun from → permit.

  پرموتش، جایگشت   
permuteš, jâygašt

Fr.: permutation   

Math.: A rearrangement of the elements of a set in a particular order. The number of permutations of n objects is equal to n! (→ factorial n). For example, there are 24 permutations of letters A, B, C, and D (4! = 1 × 2 × 3 × 4). The number of permutations of n objects taken r at a time is denoted by nPr and equals n! / (n - r)!. For example, the number of permutation of A, B, C, and D taken two at a time is 12. If n objects are of k different kinds, with r1 alike of one kind, permutations of n objects equals n! / r1! r2! ... rk!, where r1 + r2 + ... rk = n.

Verbal noun of → permute.

Permuteš, verbal noun of → permute.
Jâygašt , from "place" (from Mid.Pers. giyag "place;" O.Pers. ā-vahana- "place, village;" Av. vah- "to dwell, stay," vanhaiti "he dwells, stays;" Skt. vásati "he dwells;" Gk. aesa (nukta) "to pass (the night);" Ossetic wat "room; bed; place;" Tokharian B wäs- "to stay, wait;" PIE base ues- "to stay, live, spend the night") + gašt past tense of gaštan, gardidan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend").


Fr.: permuter   

M.E., from L. permutare "to change throughout," from per- "through" + mutare "to change," from PIE base *mei- "to change, go, move;" cf. Av. miθô "inverted, false," miθaoxta- "wrong spoken;" Skt. methati "changes, alternates, joins, meets," mith- "to alternate, meet," mithás "opposite, in opposition;" L. meare "to go, pass," mutuus "done in exchange;" Goth. maidjan "to change;" E. prefix mis- (in mistake).

Permutidan, from permute, as above.


Fr.: perpendiculaire   

A line or plane at right angles to another line or plane. Two curves are said to be perpendicular if their tangent lines are mutually perpendicular. → normal; → vertical

From M.E. perpendiculer(e), from O.Fr. perpendiculiere, from L. perpendicularis "vertical, as a plumb line," from perpendiculum "plumb line," from perpendere "balance carefully," from per- "thoroughly" + pendere "to weigh, to hang."

Pâlâr "pillar, column, main beam."

perpendicular axis theorem
  فربین ِ آسه‌ها‌ی ِ پالار   
farbin-e âsehâ-ye pâlâr

Fr.: théorème des axes perpendiculaires   

The → moment of inertia of a plane object (→ lamina) about an axis perpendicular to the plane is equal to the sum of the moments of inertia about any two perpendicular axes in the plane. Thus if x and y axes are in the plane, Iz = Ix + Iy.

perpendicular; → axis; → theorem.

hamišegi (#)

Fr.: perpétuel   

Lasting an indefinitely long time; eternal; permanent. → perpetual motion; → perpetual calendar.

M.E. perpetuall, from O.Fr. perpetuel, from L. perpetualis "permanent," from perpetuus "continuous, universal," from perpetis, genitive of Old L. perpes "lasting;"

Hamišegi from hamišé "always;" Mid.Pers. hamišag, from anôšag "immortal," from Av. an-aoša-, from negation prefix → an- + aošah- "death; ruin; corruption" (Mid.Pers. hôš "death;" Mod.Pers. hôš, huš "death; mind; intellect"); cf. derivatives Sogd. nôšé "immortal," nôšak "always;" Mod.Pers. nôš, nuš "the water of immortality; sweet; honey."

perpetual calendar
  گاهشمار ِ همیشگی   
gâhšomâr-e hamišegi

Fr.: calendrier perpétuel   

A chart or mechanical device that indicates the day of the week for any given date over a period of many years.

perpetual; → calendar.

perpetual motion
  جنبش ِ همیشگی   
jonbeš-e hamišegi

Fr.: mouvement perpétuel   

The motion of a hypothetical machine which, once set in motion, will go on for ever without any losses due to → friction or other forms of → dissipation of energy and without receiving any external energy.

perpetual; → motion.


Fr.: Perséides   

A → meteor shower, one of the three most active of the year, which occurs between July 25 and August 20 with the greatest activity between August 8 and 14, peaking about August 12. The Perseids appear as the Earth's orbit around the → Sun crosses the dusty tail of the comet → Swift-Tuttle, as first explained by Giovanni Schiaparelli (1835-1910), an Italian astronomer. Usually about 50 meteors can be seen per hour, but in outburst years (such as in 2016) the rate can be between 150-200 meteors an hour.

Perseus + -ids.

Perseus (#)

Fr.: Persée   

The Hero. A rich constellation in the northern hemisphere between → Auriga and → Cassiopeia, at 3h 20m right ascension, 45° north declination. Beta (β) Persei, or → Algol, is a famous → eclipsing binary star. Abbreviation: Per; genitive: Persei.

The most celebrated of the Greek heroes, the son of Zeus and Danae, who slew the Gorgon Medusa, and afterward saved Andromeda from a sea monster.

Perseus, from Gk., as above, instead of the Arabicized form Barsâvuš (برساووش).

Perseus A
  پرسءوس A   
Persus A

Fr.: Perseus A   

A → radio source in the constellation → Perseus, identified with the supergiant elliptical galaxy → NGC 1275.


Perseus Arm
  بازوی ِ پرسءوس   
bâzu-ye Perseus

Fr.: Bras de Persée   

One of the spiral arms of the Galaxy. It is about 5000 light-years farther from the center than the local Orion Arm, in which the Sun lies.

Persus; → arm.

Perseus Cluster
  خوشه‌ی ِ پرسءوس   
xuše-ye Perseus

Fr.: amas de Persée   

A → galaxy cluster of about 12,000 members about 250 million → light-years (→ redshift z = 0.0176) away, covering 4° of sky in the constellation → Perseus. It is dominated by elliptical galaxies. At its center lies the → radio sourcePerseus A. Also known as Abell 426 (→ Abell catalog).

Perseus; → cluster.

Perseus-Pisces supercluster
  ابرخوشه‌ی ِ پرسءوس-ماهی   
abarxuše-ye Perseus-Mâhi

Fr.: superamas de Persée-Poissons   

A long, dense chain of galaxies with a length of almost 300 million → light-years, constituting one of the largest known structures in the → Universe. At the left end of the supercluster lies the massive → Perseus cluster (A426), one of the most massive clusters of galaxies within 500 million light-years.

Perseus; → Pisces; → cluster.

Persian calendar
  گاهشمار ِ ایرانی   
gâhšomâr-e Irâni (#)

Fr.: calendrier persan   

Same as → Iranian calendar.

Persian, adj. of Persia, from O.Pers. Pārsa.

Irâni adj. of Irân, from Mid.Pers. Êrân "(land of) the Aryans," pluriel of êr "noble, hero," êrîh "nobility, good conduct;" Parthian Mid.Pers. aryân; O.Pers. ariya- "Aryan;" Av. airya- "Aryan;" cf. Skt. ārya- "noble, honorable, respectable."


Fr.: persister   

1) To continue steadfastly or firmly in some state, purpose, course of action, or the like, especially in spite of opposition, remonstrance, etc.
2) To last or endure tenaciously (

M.Fr. persister, from L. persistere "abide, continue steadfastly," from → per- "thoroughly" + sistere "come to stand, cause to stand still," → resist.

Paristâdan from par-, → per-, + istâdan "to stand," → resist.

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