An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A → Freidmann-Lemaitre  → cosmological model in which → space is → infinite and of → negative  → curvature or → Euclidean, and which expands forever.

→ open; → universe.

In → predicate logic, a → well-formed formula with one or more → free occurrences of → variables.

→ open; → wff.

The capability of being put into use, operation, or practice.

→ operable; → -ity.

Capable of operating or of being operated.

→ operate; → -able.

To function or work; to make something function or work.

From L. operari "to work, labor," L. opus "a work, labor, exertion," Av. *āpah-, *apah- "to do, operate," see below, Skt. ápas- "work, action, religious act;" O.H.G. uoben "to start work, to practice, to honor;" Ger. üben "to exercise, practice;" Du. oefenen; O.E. æfnan "to perform, work, do," afol "power"); PIE base *op- "to work, perform."

Âpâridan, from âpâr-, from Av. *āp(ah)- "to do, operate," as above, + suffix -ar (as in vadar- "weapon," zafar- "jaw," baēvar- "thousand," and so on), shifted to -âr, + -idan suffix of infinitives. The Av. *āpah- "to do, operate," is extant in Mod.Pers. xub "good;" Mid.Pers. hwp, xub "good;" from Av. huuāpah- "doing good work, masterly," from huu-, hv- "good" → eu- + āpah- "work, deed," hauuapanha- "creativity;" cf. Skt. sv-ápas- "doing good work, skillful;" PIE base *op-, as above.

The program that, after being initially loaded into the → computer by a boot program, → manages all the other → programs in a computer.

→ operating; → system.

1) General: An act or instance, process, or manner of functioning or operating.
2a) Math.: A mathematical process, as addition, multiplication, or differentiation.
2b) The action of applying a mathematical process to a quantity or quantities.
3) Computers: An action resulting from a single instruction.

Verbal noun of → operate

Pertaining to a process or series of actions for achieving a result.

Adj. of → operation.

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.

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.

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.

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.

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").

To hold or express an opinion.

Verb for → opinion.

1) A belief or judgment that rests on grounds insufficient to produce complete certainty.
2) A personal view, attitude, or appraisal.
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 Pashto pažân / pêžân, from prefix- pa-, originally *pati-, + žân variant of Pers. dân-, dânestan "to know," zân as in farzâne "intelligent, wise;" Balochi zân, Kurd. zân "to know;" cf. Sogd. patzân, Khotanese paysân- "to know;" Yidgha and Munji vəzân "to know;" Yizghulami vəzan, Yaghnobi bīzon, Sarigholi pajan, Ormuri pazán "to know;" Av. paiti-zan- "to recognize, acknowledge, appreciate;" from prefix paiti- + zan- "to know, have knowledge;" Mod.Pers. dân-, dânestan "to know," variant šenâxtan "to know, recognize," → science.

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.

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.

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.

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.

A person who adapts his actions, responses, etc, to take advantage of opportunities, circumstances, etc. (Dictionary.com).

→ opportune + → -ist.