An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>

Number of Results: 13116 Search : far
ton
  تن   
ton (#)

Fr.: tonne   

A → metric unit of → mass, equal to 1000 → kilograms.

M.E. tunne unit of weight or capacity (cf. O.Fris. tunne, M.Du. tonne, O.H.G. tunna, Ger. tonne), also found in M.L. tunna and O.Fr. tonne, perhaps from a Celtic source.

tone
  تن   
ton (#)

Fr.: son   

A musical sound of definite pitch, consisting of several relatively simple constituents called partial tones, the lowest of which is called the fundamental tone and the others harmonics or overtones.

M.E., from O.Fr. ton, from L. tonus "a sound, tone, accent," literally "stretching," from Gk. tonos "vocal pitch, raising of voice," related to teinein "to stretch," cognate with Pers. tanidan "to spin, weave," → tension.

Ton, loan from Fr., as above.

Toomre criterion
  سنجیدار ِ تومره   
sanjidâr-e Toomre

Fr.: critère d'Ostriker-Peebles   

A criterion for the stability of the disk of a → spiral galaxy. It is expressed by the → Toomre parameter.

Toomre criterion; → criterion.

Toomre length
  درازای ِ تومره   
derâzâ-ye Toomre

Fr.: longueur de Toomre   

The scale beyond which for a thin, rotating disk, rotation stabilizes self-gravitational contraction. The Toomre length is given by: λT = 4π2GΣ / κ2, where G is the → gravitational constant, Σ is the mass → surface density, and κ is the → epicyclic frequency (Toomre 1964, ApJ 139, 1217).

Toomre parameter; → length.

Toomre parameter
  پارامون ِ تومره   
pârâmun-e Toomre

Fr.: paramètre de Toomre   

A quantity that measures the stability of a differentially rotating disk of matter against → gravitational collapse. It is expressed by the relation: Q = csκ / πGΣ, where cs is the → sound speed, κ the → epicyclic frequency, G the → gravitational constant, and Σ the → surface density. The disk is linearly stable for Q > 1 and linearly unstable for Q < 1.

After Alar Toomre (1936-), an American astrophysicist of Estonian origin, professor of mathematics at the Massachusetts Institute of Technology; → parameter.

toothed-wheel experiment
  آزمایش ِ چرخ ِ دندانه‌دار   
âzmâyeš-e carx-e dandâne-dâr

Fr.: expérience de la roue dentée   

The experiment which provided the first accurate measurement of the speed of light. The experiment, conducted by the French physicist Armand H. L. Fizeau (1819-1896) in 1849, used a rotating wheel containing 720 teeth. The function of the wheel was to cut a light beam into short pulses and to measure the time required for these pulses to travel to a distant mirror and back (17.34 km). The round-trip time for each pulse could be calculated to be about 1/18,000 sec, which yielded the value of 315,300 km/sec for the speed of light. Leon Foucault (1819-1868) improved on Fizeau's method by replacing the cogwheel with a rotating mirror. Foucault's estimate, published in 1862, was 298,000 km/s.

From tooth; M.E.; O.E. toth (cf. O.S., Dan., Swed., Du. tand, O.N. tönn, O.Fris. toth, O.H.G. zand, Ger. Zahn, Goth. tunthus), cognate with Pers. dandân, as below; → wheel; → experiment.

Âzmâyeš, → experiment; carxwheel; dandâne-dâr "toothed," from dandân "tooth," Mid.Pers. dandân; Av. dantan-; cf. Skt. dánta-; Gk. odontos; L. dens (Fr. dent); Lith. dantis, O.Ir. det, Welsh dent; PIE base *dont-/*dent- "tooth."

top
  بالا   
bâlâ (#)

Fr.: sommet, du haut, haut   

The highest point or part. The higher end of anything on a slope.

M.E., O.E. top "summit, crest, tuft;" cf. O.N. toppr "tuft of hair," O.Fris. top "tuft," O.Du. topp, Du. top, O.H.G. zopf "end, tip, tuft of hair," Ger. Zopf "tuft of hair."

Bâlâ "up, above, high, elevated, height" (variants boland "high, tall, elevated, sublime," borz "height, magnitude" (it occurs also in the name of the mountain chain Alborz), Laki dialect berg "hill, mountain;" Mid.Pers. buland "high;" O.Pers. baršan- "height;" Av. barəz- "high, mount," barezan- "height;" cf. Skt. bhrant- "high;" L. fortis "strong" (Fr. and E. force); O.E. burg, burh "castle, fortified place," from P.Gmc. *burgs "fortress;" Ger. Burg "castle," Goth. baurgs "city," E. burg, borough, Fr. bourgeois, bourgeoisie, faubourg; PIE base *bhergh- "high."

top-down structure formation
  دیسش ِ ساختار از بالا به پایین   
diseš-e sâxtâr az bâlâ bé pâyin

Fr.: formation des structures du haut vers le bas   

A cosmological model of → structure formation in which larger structures, such as galaxy → superclusters or perhaps even the vast → filaments and → voids, form earlier and then they fragment into smaller structures such as individual galaxies. Opposite of → bottom-up structure formation.

top; → down; → structure; → formation.

top-heavy IMF
   IMF ِ بالا-سنگین   
IMF-e bâlâ-sangin

Fr.:   

A star formation process in which → massive stars form more abundantly than that predicted by standard models, whereby the top end of the → initial mass function is significantly flatter than the canonical → Salpeter slope.

top; → heavy; → initial mass function.

topic
  بارک   
bârak

Fr.: sujet, thème   

1) The subject of a discourse or of one of its parts.
2) The main and explicit subject matter of a literary work, often composed of several themes.

From L. topica, from Gk. topikos "pertaining to a common place, of a place," from topos "a place."

Bârak, from bâre "subject, matter, meaning," as in dar bare-ye "in the matter of; about," + nuance suffix -ak.

topocentric coordinates
  هماراهای ِ جا-مرکزی   
hamârâhâ-ye jâ-markazi

Fr.: coordonées topocentriques   

A coordinate system that uses the observer's location as its central reference point. Usually, the difference in the position of an object in the sky measured using topocentric and geocentric coordinates is very small because most celestial objects are so far away. However, for nearby objects this is not true. The Sun, for example, may appear displaced as much as eight arcseconds from its geocentric position, and the Moon by as much as one degree.

Topocentric, from topo- combining form of Gk. topos "place" + centric, from → center; → coordinate.

Hamârâhâ, → coordinate; jâ-markazi "topocentric," from "place" (from Mid.Pers. giyâg "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") + markazi, of, pertaining to markaz, → center.

topological
  توپوشناختی، توپوشناسیک   
topošenâxti, topošenâsik

Fr.: topologique   

Of or relating to → topology.

topology; → -ic; → -al

topological defect
  آک ِ توپوشناختی، ~ توپوشناسیک   
âk-e topošenâxti, ~ topošenâsik

Fr.: défaut topologique   

In → cosmological models, a stable configuration of → matter formed when the → early Universe underwent → phase transitions during which fundamental symmetries were broken. There are a number of possible types of defects, such as domain walls, → cosmic strings, → magnetic monopoles, and → texture s. Same as → cosmic defect.

topological; → defect.

topological space
  فضای ِ توپوشناختی   
fazâ-ye topošenâxti

Fr.: espace topologique   

A set X together with a collection of open subsets T that satisfies the three following conditions: 1) The empty set Ø and X are in T. 2) The intersection of a finite number of sets in T is also in T. 3) The union of an arbitrary number of sets in T is also in T.

topological; → space.

topology
  توپوشناسی   
topošenâsi

Fr.: topologie   

The study of the properties of geometric figures that remain invariant under certain transformations, as bending or stretching. A circle is topologically equivalent to an ellipse (into which it can be deformed by stretching) and a sphere is equivalent to an ellipsoid.

From topo- combining form of Gk. topos "place" + → -logy.

Topošenâsi, from topo-, loan from Gk., as above, + šenâsi-logy.

torch
  آهیر   
âhir (#)

Fr.: torche   

A light to be carried in the hand, consisting of some combustible substance, as resinous wood, or of twisted flax or the like soaked with tallow or other flammable substance, ignited at the upper end (Dictionary.com).

M.E. torche, from O.Fr. torche "torch," originally "twisted thing," then "torch formed of twisted tow dipped in wax," probably from V.L. *torca, alteration of L.L. torqua, from torquere "to twist," → torque.

Âhir, from Kurd. âhir "torch," variant of âzar, → fire.

Torino scale
  مرپل ِ تورین   
marpel-e Turin

Fr.: échelle de Turin   

A scale used to assess the threat posed by the → impact of a → near-Earth object (NEO). It considers the impact energy as well as the probability of impact. It is designed to communicate to the public the risk associated with a NEO in more qualitative form than the → Palermo scale. The → impact hazard is expressed by a number between 0 and 10 depending on the probability that an impact will occur and the kinetic energy of the potential → impactor. The extent of damage ranges from inconsequential (0) to catastrophic (10). The scale is color-coded such that white = no consequence; green = meriting careful monitoring; yellow = meriting concern; orange = threatening events; red = impact is certain.

Named for Torino, because the scale was adopted by that city in Italy in 1999; → scale.

tornado
  پیچ-توف، توفان ِ پیچنده   
pic-tuf, tufân-e picandé

Fr.: tornade   

A mass of rotating air with high wind speeds at its center. It is produced in a very severe thunderstorm and appears as a funnel cloud extending from the base of a Cumulonimbus to the ground.

Tornado, metathesis from Sp tronada "thunderstorm," from tronar "to thunder," from L. tonare "to thunder," → thunder.

Pic-tuf, from pic present stem of picidan "to twist, entwine, coil" (Mid.Pers. pecidan "to twist, entwine") + tuf short for tufân, → storm.
Tufân-e picandé, from tufânstorm + picandé agant noun/adj. of picidan

toroid
  چنبروار   
cambarvâr (#)

Fr.: toroïde   

A surface of revolution obtained by rotating a closed plane curve about an axis parallel to the plane which does not intersect the curve. The simplest toroid is the → torus. The solid enclosed by such a surface.

From tor-, from → torus + → -oid.

toroidal magnetic field
  میدان ِ مغناتیسی ِ چنبروار   
meydân-e meqnâtisi-ye cambarvâr

Fr.: champ magnétique toroïdal   

A magnetic field which is generated in a → plasma inside a → toroid, as in a → tokamak, by the electric current which spirals around the toroid. Toroidal field has no radial component. → poloidal magnetic field.

toroid; → magnetic field.

<< < -es -iv -ti 21 a p abe abs abs aca acc acc acr act ada adh Adr aer aga air Alf Alg alk Alp alt alu amm ana And ang ani ano ant ant Ap apo app app Aqu Arc arg arr asc ass ast ast asy atm ato att aur aut axi B-m bad Bal bar bar Bay Bed ber Bet bif bim bin bio bis bla ble blu Bod Bol bor bou Bra Bre bro bul C-t Cal Cam can car Car Cas cat cav cel cen cer Cha cha Cha che chl Cir cir cir Cla cli clo clu co- coc coh col col col Com com com com com com com com Com con con con con con con con con con con con con coo Cor Cor cor cos cos cos Cou cou Cra Cre cri cro cub cur cyc cyl Dan dat Dav de- Deb dec dec dee def deg del Den den der det deu dew dic dif dif dil Dip dir dis dis dis dis dis diu dod Dop dou Dra dua dus dwa dyn DZ Ear ecc eco edi EHB Ein ela ele ele ele ele ell eme emp end Eng ent epi equ equ era ESP eth Eur evi exa exc exe exi exp exp ext ext ext fac fal far fec Fer fer fie fin fir fis fla Flo flu fog for for Fou fra fre fre Fro fun G s Gal gal gal Gar gau geg gen geo geo geo ger gla gly gra gra gra gra gra Gre gro GYR Had Hal hap Har HD hea hel hel Hen Her hex hig Hil hol Hoo hor hou Hub hum hyb hyd hyd hyp hys ide ign ima imp imp in- inc Ind ind ine inf inf inf ini ins ins ins int int int int Int int int int inv ion iri irr iso iso iso Jea Jor jum K c Kep Ker kin kno lab Lam Lan Lap las lat Le lef len lev lig lig lin lin lin liq Lit loc log lon lou LS lun lun Lym M s Mag mag mag mag mag mag maj man Mar mas mas mat May mea mec mel mer mes met met met mic mid mil Min Mir mix mod mod mol mon mor mov mul mur mys nan nat nav nec Nep neu New New NGC nob nom non non nor nos nuc nuc num nut obj obl obs occ oct off oli oni ope opp opt opt orb ord org orp osc out ove oxi P-w pal par par par par Pas pat pej per per per per per per pha Phe pho pho pho phy pin pla Pla pla pla pla plu poi pol pol Pol pol por pos pot Poy pre pre pre pre pri pri pri pro pro pro pro pro pro Psa pul pum Q i qua qua qua qua R A rad rad rad rad rad rad Ram Ran rat rea rea rec rec red red ref ref reg rei rel rel rem rep res res res ret rev Rho Rie ril riv rog Ros rot rul S A Sag sam sat sca sca Sch Sco Sec sec sec seg sel sem sen set Sha sha shi sho sid sig sim sin Sir ske sli Smo soc sof sol sol sol sol sou sou spa spe spe Spe spe sph spi Spi spr sta sta sta sta sta ste ste ste Sto str str sub sub sub suc sun sup sup sup sup sur swa syn syn tac tas tel tem ter tes the the the the thi thr tid til tip ton tor tou tra tra tra tra Tri tri tru tsu tur two Typ UHE ult unc uni uni uni upg ura uti val var vec Vel ver Ver vie Vir vis vis vol W-R war wav wav wea Wei wha wid win WN3 Wol wri xen yok zen zij > >>