# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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 operational calculus   افماریکِ آپارشی   afmârik-e âpârešiFr.: calcul opérationnel   A method of mathematical analysis which in many cases makes it possible to reduce the study of differential operators, pseudo-differential operators and certain types of integral operators, and the solution of equations containing them, to an examination of simpler algebraic problems. It is also known as operational analysis.→ operational; → calculus. operationalism   آپارش‌باوری   âpârešbâvariFr.: opérationalisme   In the philosophy of science, the view that → concepts are defined in terms of measuring operations which determine their applicability. Same as operationism.→ operation; → -ism. operator   آپارگر   âpârgarFr.: opérateur   Math.: Something that acts on another function to produce another function. In linear algebra an "operator" is a linear operator. In calculus an "operator" may be a differential operator, to perform ordinary differentiation, or an integral operator, to perform ordinary integration.From → operate; + → -or. Ophelia   ا ُفلیا   Ofeliyâ (#)Fr.: Ophélie   A small satellite of → Uranus, the second nearest to the planet, discovered from the images taken by the Voyager 2 spacecraft in 1986. Also denoted Uranus II, it has a diameter of 32 km. Ophelia is one of the two → shepherd moons that keep the planet's Epsilon ring, the other being → Cordelia.Ophelia is the daughter of Polonius in Shakespeare's Hamlet. Ophiuchus   مار‌افسا   Mâr-afsâ (#)Fr.: Ophiuchus   The Serpent Holder. An extensive constellation located in the equatorial regions of the sky at about 17h 20m right ascension, 5° south declination. Although this constellation is not part of the zodiac, the Sun passes through it in December each year. Ophiuchus contains five stars of second magnitude and seven of third magnitude. Other designations: Serpent Bearer, Serpentarius. Abbreviation: Oph, genitive: Ophiuchi.L. Ophiuchus, from Gk. ophioukhos "holding a serpent," from ophis "serpent" + echein "to hold, have, keep." The most recent interpretation is that the figure represents the great healer Asclepius, a son of the god Apollo, who learned the secrets of keeping death at bay after observing one serpent bringing another healing herbs. To prevent the entire human race from becoming immortal under Asclepius' care, Zeus killed him with a bolt of lightning, but later placed his image in the heavens to honor his good works.Mâr-afsâ "a tamer or charmer of serpents; one who cures the snake-bitten by incantation," from mâr "snake, serpent" (Mid.Pers. mâr "snake;" Av. mairya- "snake, serpent") + afsâ agent noun of afsâyidan, from afsun "incantation" (Mid.Pers. afsôn "spell, incantation," afsûdan, afsây- "to enchant, protect by spell"). opine   پژانیدن   pažânidanFr.: être d'avis que   To hold or express an opinion.Verb for → opinion. opinion   پژان   pažânFr.: opinion   1) A belief or judgment that rests on grounds insufficient to produce complete certainty (Dictionary.com). See also: → public opinion. 2) A personal view, attitude, or appraisal (Dictionary.com). 3) Law: The formal statement by a judge or court of the reasoning and the principles of law used in reaching a decision of a case (Dictionary.com).M.E., from O.Fr., from L. opinion- "opinion, conjecture; appreciation," from opinari "to think, judge, suppose," from PIE *op- "to choose."Pažân, from Pashtu pežân, Sogd. patzân, Khotanese paysân- "to know;" Av. paiti-zan- "to recognize, acknowledge, appreciate;" from prefix paiti- + zan- "to know, have knowledge;" cf Mod.Pers. farzâné "intelligent; wise," dân-, dânestan "to know," variant šenâxtan "to know, recognize," → science. Oppenheimer-Volkoff limit   حدِ ا ُپنهایمر-وُلکوف   hadd-e Oppenheimer-VolkoffFr.: limite d'Oppenheimer-Volkoff   The upper bound to the mass of a → neutron star, the mass beyond which the pressure of neutron → degenerate matter is not capable of preventing the → gravitational collapse which will lead to the formation of a → black hole. Modern estimates range from approximately 1.5 to 3.0 → solar masses. The uncertainty in the value reflects the fact that the → equation of state for → overdense matter is not well-known.Oppenheimer, J.R., Volkoff, G.M., 1939, Physical Review 55, 374. Named after Robert Oppenheimer (1904-1967), an American theoretical physicist, and George Volkoff (1914-2000), a Canadian physicist, who first calculated this limit. Oppenheimer is widely known for his role as the scientific director of the Manhattan Project, the World War II effort to develop the first nuclear weapons at the secret Los Alamos laboratory in New Mexico; → limit. opponent   پادیستگر   pâdistgarFr.: opposant, adversaire   A person who is on an opposing side in a game, contest, controversy, or the like; adversary (Dictionary.com).L. opponent-, p.p. of opponere "to oppose, to object to," literally "set against, set opposite," from op- variant of ob- before p "against" + ponere "to put, set, place," → position.Pâdistgar, from pâdist, → opposition, + -gar, → -or. opportune   نیکوا   nikvâFr.: opportun   1) Appropriate, favorable, or suitable. 2) Occurring or coming at an appropriate time; well-timed (Dictionary.com).M.E., from O.Fr. opportun and directly from L. opportunus "fit, convenient, suitable," from the phrase ob portum veniens "coming toward a port," literally "a wind blowing to harbor," from ob "to, toward" + portus "access, harbor."Nikvâ "appropriate, suitable," from nik, nêk, neku "good, beautiful, elegant;" Mid.Pers. nêk, nêvak, nêkôg "good, beautiful;" O.Pers. naiba- + -vâ relation suffix (as in pišvâ, pilévâ); alternatively, nikvâ "good/appropriate wind," from nik + vâ "wind," variant of bâd, → wind, in several dialects. opportunism   نیکواگرایی   nikvâgerâyiFr.: opportunisme   The policy or practice, as in politics, business, or one's personal affairs, of adapting actions, decisions, etc., to expediency or effectiveness regardless of the sacrifice of ethical principles (Dictionary.com).→ opportune + → -ism. opportunist   نیکواگرا   nikvâgerâFr.: opportuniste   A person who adapts his actions, responses, etc, to take advantage of opportunities, circumstances, etc. (Dictionary.com).→ opportune + → -ist. opportunity   نیکوایی   nikvâyiFr.: opportunité   1) An appropriate or favorable time or → occasion. 2) A situation or condition favorable for attainment of a goal (Dictionary.com).→ opportune + → -ity. oppose   پادیستیدن   pâdistidanFr.: s'opposer à, faire opposition à; opposer   1) To act against or provide resistance to. 2) To stand in the way of; hinder; obstruct (Dictionary.com).M.E., from O.Fr. oposer "to oppose, resist; contradict," from poser "to place, lay down," blended with L. opponere "to oppose, to object," → position.Pâdistidan, infinitive from pâdist, → opposition. opposite   ۱) رو-به-رو؛ ۲) پادیستین؛ ۳) پادچم   1) ru-be-ru; 2) pâdistin; 3) pâdcemFr.: 1) opposé, d'en face; 2) contraire, opposé; 3) antonyme   1) Situated, placed, or lying face to face with something else or each other, or in corresponding positions with relation to an intervening line, space, or thing: opposite ends of a room (Dictionary.com). 2) Contrary or radically different in some respect common to both, as in nature, qualities, direction, result, or significance; opposed (Dictionary.com). 3) An → antonym.M.E., from M.Fr., from L. oppositus, p.p. of opponere, → opposition.1) Ru-be-ru "face to face," → surface. 2) Pâdistin, from pâdist, → opposition, + -in, as in zirin, zebarin, pišin, pasin. 3) Pâdcem, → antonym. opposition   ۱، ۲) پادیست؛ ۳، ۴) پادیستان   1, 2) pâdist; 3, 4) pâdistânFr.: opposition   1) The action of opposing, resisting, or combating. 2) A person or group of people opposing, criticizing, or protesting something, someone, or another group (Dictionary.com). 3) The position of a solar system body having its orbit outside that of the Earth when the Earth is in a line between the Sun and the body. At opposition the body has a solar → elongation of 180°, and is closest to the Earth. It will, in principle, be visible throughout the night. It will rise in the east as the Sun sets in the west and it will set as the Sun rises. This is because, at opposition, the body and the Sun are 12 hours apart. The inner planets can never be in opposition. The opposite of opposition is → conjunction. 4) Two periodic quantities of the same frequency are said to be in opposition when the → phase difference between them is one half of a → period.Verbal noun of → oppose.Pâdist "standing against," from pâd- "agaist, contrary to," → anti-, + ist present stem of istâdan "to stand" (Mid.Pers. êstâtan, O.Pers./Av. sta- "to stand; to set;" Av. hištaiti; cf. Skt. sthâ- "to stand;" Gk. histemi "put, place, weigh," stasis "a standing still;" L. stare "to stand;" Lith. statau "place;" Goth. standan; PIE base *sta- "to set, stand"). Pâdistân, from pâdist + -ân suffix of place and time. oppress   ستمیدن   setamidan (#)Fr.: opprimer   To burden with cruel or unjust impositions or restraints; subject to a burdensome or harsh exercise of authority or power (Dictionary.com).M.E. oppressen, from O.Fr. opresser "oppress, torment, smother," from M.L. oppressare, from L. opprimere "press against, press together, press down; subdue, prosecute relentlessly," from op variant of ob "against" + premere "to press, hold fast."Infinitive from setam, → oppression. oppression   ستم   setam (#)Fr.: oppression   1) The exercise of authority or power in a burdensome, cruel, or unjust manner. 2) An act or instance of oppressing or subjecting to cruel or unjust impositions or restraints. 3) The state of being oppressed (Dictionary.com).M.E. oppressioun, from O.Fr. opresser "oppress; torment," from M.L. oppressare, from L. opprimere "press against, press down;" from op, variant of ob "against" + premere "to press, hold fast."Setam, from Mid.Pers. sthmbk / stambag / "oppressive; obstinate," related to sitabr "strong, firm," staft "hard; firm, strong; fierce," Pers. seft "firm, hard, tight;" sitanbah "strong, robust, bold;" Av. aša.stəmbana- "having the support/firmness of aša;" Lith stembti "to oppose;" Gk. astemphes "unshakable." opt   اپتیدن   optidanFr.: opter   To make a choice; choose (usually followed by for).From Fr. opter "to choose," from L. optare "to choose, desire, wish for," from L. optare "to desire, choose," from PIE root *op- "to choose, prefer."Optidan, from L. optare, as above. optative   اپتانه، اپتمند   Fr.: optatif   Of, relating to, or constituting a verbal mood that is expressive of wish or desire.From M.Fr. optatif, from L. optativus, from optatus, p.p. of optare, → opt, + -ivus, → -ive.Optâné, optmand, from opt present stem of optidan, → opt, + adj. suffixes -âné, -mand. -yi.