An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



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Number of Results: 378
obtuse angle
  زاویه‌ی ِ باز   
zâviye-ye bâz (#)

Fr.: angle obtus   

An angle whose measure is greater than 90° and less than 180°.

Obtuse, from M.Fr. obtus (fem. obtuse), from L. obtusus "blunted, dull," p.p. of obtundere "to beat against, make dull," from ob "against" + tundere "to beat," from PIE *(s)tud- "to beat, strike, push, thrust;" → angle.

Zâviyé, → angle; bâz "open," from Mid.Pers. abâz-, apâc-, O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind."


Fr.: occasion   

1) A particular time, especially as marked by certain circumstances or occurrences.
2) A special or important time, event, ceremony, celebration, etc.
3) A convenient or favorable time, → opportunity, or juncture (

M.E. occasioun from O.Fr. ochaison, ocasion "cause, reason, pretext; opportunity," from L. occasionem (nominative occasio) "appropriate time," from occasum, occasus "fall; sunset," p.p. of occidere "fall down, go down," from ob "down, away" + cadere "to fall," → case.

Âkatan, from prefix â- + katan "to fall," cf. Laki: katen "to fall," kat "he/she fell," beko! "fall!" (an insult); katyâ "fallen;" Lori: kat "event, error;" Kurd. (Soriani): kawtin "to fall, befall," kett "fallen;" Kurd. (Kurmanji): da.ketin "to fall down;" Lârestâni: kata "to fall;" Garkuyeyi: darkat, varkat "he/she fell (sudden death);" Gilaki (Langarud, Tâleš): katan "to fall," bakatam "I fell," dakatan "to fall (in a marsh, in a pit)," vakatan "to fall from tiredness, be exhausted," fakatan "to fall from (i.e., lose) reputation;" Tabari: dakətə "fallen," dakətən "to crash down," dakə "stray cow;" Proto-Iranian *kat- "to fall;" cf. L. cadere "to fall," → case, Pers. kâté.


Fr.: occasionnel   

1) Occurring or appearing at irregular or infrequent intervals; occurring now and then.
2) Intended for supplementary use when needed.
3) Pertaining to, arising out of, or intended for the occasion (

occasion; → -al.


Fr.: Occator   

An → impact crater on the → dwarf planet  → Ceres. It has a diameter of about 90 km and a depth of about 4 km.

Named after the Roman agriculture deity of harrowing, a method of leveling soil.


Fr.: occultation   

The blocking of light from an astronomical object, such as a star, by another object, such as the Moon or an asteroid, that passes in front of it. Also, the period of time for which this blocking takes place. A → solar eclipse is a particular case of occultation. Determining the moment of stellar occultation by the Moon is used to improve our knowledge of the lunar orbit. Moreover, the occultation of stars by asteroids or planetary satellites provide important data for better measuring the sizes of the occulting bodies. See also → grazing occultation.

M.E. from L. occultation- "a hiding," from occultat(us), p.p. of occultare "to conceal, keep something hidden," frequentative of occulere "to cover over, conceal," from ob "over" + a verb related to celare "to hide," from PIE base *kel- "to conceal."

Forupušân, from foru- "down, downward; below; beneath" (Mid.Pers. frôt "down, downward;" O.Pers. fravata "forward, downward;" cf. Skt. pravát- "a sloping path, the slope of a mountain") + pušân of pušândan, accusative of pôšidan, pôš- "to cover; to wear" (related to pust "skin, hide;" Mid.Pers. pôst; O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth").


Fr.: occupation   

The act of occupying; the state of being occupied.

Verbal noun of → occupy.

occupied level
  تراز ِ هَگیده   
tarâz-e hagidé

Fr.: niveau occupé   

The energy level adopted by a particle, atom, or molecule under quantum mechanical laws.

Occupied, p.p. of → occupy; → level.


Fr.: occuper   

To take or fill up (space, time); to take possession and control of a place.

From O.Fr. occuper, from L. occupare "take over, seize, possess, occupy," from ob "over" + intensive form of capere "to grasp, seize, take;" PIE base *kap- "to grasp" (cf. Skt. kapati "two handfuls;" Gk. kaptein "to swallow," O.Ir. cacht "servant-girl," literally "captive;" Goth. haban "have, hold;" O.E. habban "to have, hold," probably Mod.Pers. qâp-, qâpidan "to seize;" Av. haf-, hap- "to keep, observe."

Hagidan, from dialectal Pers.: Šahmirzâdi hâgetan, Saraxsi hagiton, Tabari hâytan, haytan, Semnâni hâtan, Gilaki hâgitan, Lâsgardi agiton, degiton "to occupy;" maybe related to Av. haz- "to occupy;" Skt. sah- "to overcome, be victorious, prevail," saha- "victory," sahate "overcomes, masters;" Gk. ekhein "to have, hold;" PIE base *segh- "to have, to hold."

roxdâdan (#)

Fr.: avoir lieu   

1) To happen; take place; come to pass.
2) To be found or be present; exist.

M.Fr. occurrer "to happen unexpectedly" or directly from L. occurrere "run to meet, run against, present itself," from ob "against, toward" + currere "to run," → current.

Roxdâdan, literally "to appear," from rox "appearance; aspect; face," variant ruy "face, surface" + dâdan "to give," → event.

roxdâd (#)

Fr.: événement   

1) The action, fact, or instance of occurring.
2) Something that happens; event; incident ( 3) Logic: → bound occurrence; → free occurrence.

Verbal noun of → occur.

oqyânus (#)

Fr.: océan   

The intercommunicating body of salt water occupying the depressions of the Earth's surface, or one of its major primary subdivisions, bounded by the continents, or the equator, and other imaginary lines. A sea is subdivision of an ocean. the vast body of salt water that covers almost three fourths of the earth's surface.

M.E. ocean(e), from O.Fr. occean, from L. oceanus, from Gk. okeanos "the great river or sea surrounding the disk of the Earth, as opposed to the Mediterranean," of unknown origin. Personified as Oceanus, son of Uranus and Gaia and husband of Tethys.

Oqyânus, from Ar., ultimately from Gk., as above.

ocean planet
  سیاره‌ی ِ اقیانوسی   
sayyâre-ye oqyânusi

Fr.: planète océan   

A hypothetical → exoplanet covered by a water envelope. The presence of such a planet stems from the implicit assumption of → Habitable Zone temperatures and a liquid water surface.

ocean; → planet.

oqyânusi (#)

Fr.: océanique   

Of, living in, or produced by the ocean.

ocean; → -ic.

oceanic crust
  پوسته‌ی ِ اقیانوسی   
puste-ye oqyânusi

Fr.: croûte océanique   

That part of the → Earth's crust underling most of the Earth's surface which is covered by the oceans. It has a remarkably uniform composition (mostly ~ 49% SiO2) and thickness (mostly ~ 7 km). The ocean floor is the most dynamic part of the Earth's surface. As a result, no part of the oceanic crust existing today is more than 200 million years old, which is less than 5% of the age of the Earth itself. New oceanic crust is constantly being generated from the → upper mantle by sea-floor spreading at → mid-ocean ridges, while other parts of the oceanic crust are being recycled back into the mantle at subduction zones.

oceanic; → crust.

oceanic ridge
  روک ِ اقیانوسی   
ruk-e oqyânusi

Fr.: dorsale océanique   

Any section of the narrow, continuous submarine mountain chain through all the world's oceans. The oceanic ridge constitutes the most extensive mountain ridge on Earth, more than 65,000 km. Perhaps the best-known part of the ridge system is the → Mid-Atlantic Ridge.

oceanic; → ridge.

oqyânus-šenâsi (#)

Fr.: océanographie   

The study of the ocean, embracing and integrating all knowledge pertaining to the ocean's physical boundaries, the chemistry and physics of sea water, and marine biology.

ocean + → -graphy.

Oqyânusocean + -šenâsi-logy.

oxrâ (#)

Fr.: ocre   

Any of various natural clays rich in ferric oxides (Fe2O3) and containing silica and alumina. Used as a red (→ hematite) or yellow (→ limonite) pigment.

M.E. oker, O.Fr. ocre, from L. ochra, from Gk. okhra, from okhros "pale yellow."

Oxrâ, loan from Gk.

Ockham's razor
  اُستره‌ی ِ آکم   
ostare-ye Ockham (#)

Fr.: rasoir d'Ockham   

The notion that any hypothesis should be stripped of all unnecessary assumptions. If two hypotheses fit the observations equally well, the one that makes the fewest assumptions should be chosen.

The doctrine was formulated by William of Ockham (c.1288-c.1347), an English Franciscan friar and scholastic philosopher. Razor from O.Fr. rasour "a razor," from raser "to scrape, shave."

Ostaré "razor," from sotordan "to shave, erase, remove;" Mid.Pers. ôstarak "removed, shaved," ôstârišn "wiping, shaving;" cf. Khotanese ustar- "to remove," Sogdian (prefixed *pari-) prtr- "to wipe off, dry up," from Proto-Iranian *us-tar- "to remove, wipe off."

octa-, oct-
  هشت-، اکتا-، اکت-   
hašt-, octa-, oct-

Fr.: octa-, octo-, oct-   

A prefix meaning eight.

From L. octo, Gk. okto, cognate with Pers. hašt, as below. Skt. asta, Goth. ahtau, O.E. eahta (see eight).

Hašt "eight," from Mid.Pers. hašt, O.Pers.*aštahva- "eighth;" Av. ašta; cf. Skt. astā; Ossetic ast; (Buddhist) Sogdian 'št; Gk. okto, L. octo (Fr. huit; Sp. ocho); P.Gmc. *akhto(u) (O.E. eahta, æhta, E. eight, O.N. atta, Ger. acht, Goth. ahtau); PIE base *oktô(u).
Octa-, oct, loaned Gk. forms, as above.


Fr.: octade   

A group of eight units or figures.
Chemistry: An element, atom, or group having a valence of eight.

From Gk. oktad- (stem oktás) "group of eight," from okt-oct- + -ad a prefix denoting a group or unit comprising a certain number, sometimes of years (e.g. dyad; triad).

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