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

In the Johnson → UBV system, a reddening-free parameter which is related to the → effective temperature of stars and thus provides a useful, but rough, discriminant for → spectral types. It is expressed as: Q = (U - B) - 0.72 (B - V).

→ index.

A two-dimensional figure that consists of four points connected by straight lines. Same as → tetragon; see also → quadrilateral.

L.L. quadrangulum, noun use of neuter of L. quadrangulus, quadriangulus "four-cornered," from quadr- variant of quadri- before a vowel "four," akin to quattuor, → four, cognate with Pers. cahâr, as below; → angle.

Cahârgušé, cârguš "four-cornered," from cahâr, câr "four," cognate with L. quattuor, → four, + gušé, guš "corner, angle;" Mid.Pers. gôšak "corner."

An obsolete → constellation created by the French astronomer Jérôme Lalande in 1795. He named it such for the main astronomical instrument, that is → mural quadrant, he used. Quadrans Muralis was located between the constellations → Boötes and → Draco. The name disappeared from astronomical catalogs, but the → meteor shower→ Quadrantids has kept that name.

→ mural quadrant.

1) A quarter of a circle; an arc of 90°.
2) Any of the four parts into which a plane is divided by a pair of rectangular axes.
3) An instrument, usually containing a graduated arc of 90°, formerly used in astronomy and navigation to measure the angles and altitudes of stars. → mural quadrant.

M.E., from L. quadrantem (nominative quadrans) "fourth part."

Cârakân, from cârak + -ân. Cârak "quarter," literally "fourth, a fourth part of one," from câr, variant of cahâr, → four, cognate with L. quattuor, + -ak, contraction of yak "one," from Mid.Pers. êwak (Proto-Iranian *aiua-ka-); O.Pers. aiva- "one, alone;" Av. aēuua- "one, alone" (cf. Skt. éka- "one, alone, single;" Gk. oios "alone, lonely;" L. unus "one;" E. one); -ân nuance suffix.

An annual → meteor shower reaching a peak about 3 January and having its → radiant in the constellation → Boötes.

From L. Quadrant-, from Quadrans Muralis , → mural quadrant.

Of or relating to or resembling a → square.
Of, relating to, or containing terms with powers no higher than the power of two.

Quadratic, adj. of quadrate, from L. quadratus p.p. of quadrare "to make square."

Câruši pertaining to câruš "square," from Av. caθruša- "four sides (of a four-sided figure)," from caθru- "four," Mod.Pers. cahâr, câr "four," cognate with L. quattuor, → four.

An equation with the general form of ax² + bx +c = 0, in which the highest power of the unknown is the second power (square).

→ quadratic; → equation.

A formula relating the unknown part of a → quadratic equation (the roots of the equation, x) to the known parts (a, b, and c): x = (-b± (b² - 4ac)^½) / 2a.

→ quadratic; → formula.

1) General: The process of making something square; the act of squaring.
2) Math.: The act or process of constructing a → square with an area equal to that of a specified surface, especially a surface bounded by a curve.
3) Astro.: The position of a planet or the Moon when it makes a 90° angle with the Sun as seen from Earth.

From L. quadratura, from quadrat(us) p.p. of quadrare "to make square."

1) Cârušeš verbal noun of cârušidan "to square," from câruš "square," from Av. caθruša-, → quadratic.
Câruši quality noun of câruš "square," as preceding.
2) Navadân, from navad "ninety," referring to the longitude difference of 90° (Mid.Pers. nawad; Av. nauuaiti- "ninety," from nauua- "nine" (Mod.Pers. noh); cf. Skt. navati- "ninety") + -ân suffix of place and time.

Constructing a square whose area equals that of a given circle. This was one of the three geometric problems of antiquity. It was finally proved to be an impossible problem when π was proven to be transcendental by Lindemann in 1882. Same as → squaring the circle.

→ quadrature; → circle.

A plane figure bounded by four straight lines.

From L. quadrilater(us) "four-sided," from L. quattuor, → four, + → lateral.

Fourfold; consisting of four parts.

M.E. from L. quadruplus, from quadru- + duple, from duplus, from du(o) "two" + -plus "fold."

Cahârtâ, from cahâr, → four, cognate with L. quattuor, + tâ "fold, plait, ply; piece, part" (Mid.Pers. tâg "piece, part").

A stellar system consisting of four stars orbiting around a common → center of mass.

→ quadruple; → system.

Of or pertaining to a → quadrupole, especially a → quadrupole moment.

→ quadrupole + -ar, → -al.

A set of either two → electric dipoles or two → magnetic dipoles in close proximity to each other arranged with alternating polarities and acting as a single unit. Quadrupole interactions are much smaller than dipole interactions, but can allow transitions forbidden in dipole moment transitions.

From L. quadru-, variant of quadri- "four" + → pole, on the model of → dipole.

Cahâr, → four, + qotb, → pole + noun/nuance suffix -é.

The → anisotropy which is at the origin of the → cosmic microwave background polarization. The quadrupole anisotropy could arise from three types of perturbations: → scalar perturbation, → vector perturbation, and → tensor perturbation

→ quadrupole; → anisotropy.

A device, consisting of four → electrodes or → magnetic poles arranged in alternating → polarity, that focuses a beam of → charged particles.

→ quadrupole; → lens.

A quantity characterizing an electric charge distribution, determined by the product of the charge density, the second power of the distance from the origin, and a spherical harmonic over the charge distribution.

→ quadrupole; → moment.

1) To shake or tremble.
2) The act or an instance of quaking. → earthquake, → starquake.

M.E., from O.E. cwacian "to shake, tremble," of unknown origin.

Larzidan, larz "to tremble, shiver," → seismo-.

1) A quality, accomplishment, etc., that fits a person for some function, office, or the like.
2) A circumstance or condition required by law or custom for getting, having, or exercising a right, holding an office, or the like.
3) The act of qualifying; state of being qualified (Dictionary.com).

→ qualify; → -tion.