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

Daily geometrical libration of the Moon arising from the fact that observers at different points on the Earth see the Moon from slightly different angles. As the Moon rises in the east, you are positioned on one side of our planet, and by the time it sets in the west. Earth's rotation has carried you to the other side. This change in position produces a slight → parallax effect that adds about another 1° of libration in longitude. Two other geometrical libration are → libration in longitude and → libration in latitude. See also → physical libration.

→ diurnal; → libration.

The daily apparent motion of all celestial objects, due to Earth's rotation.

→ diurnal; → motion.

The apparent difference between the position of a celestial object measured from the Earth's surface and the position that would be recorded by a hypothetical observer at the center of the Earth. Same as → geocentric parallax.

→ diurnal; → parallax.

1a) An act or instance of diving.
1b) A jump or plunge into water, especially in a prescribed way from a diving board.
2a) To go below the surface of the water, as a submarine.
2b) To → plunge into water, especially headfirst.
2c) Aeronautics: (of an airplane) to descend rapidly (Dictionary.com).

M.E. diven "to dive, dip," O.E. dufan (strong verb) "to dive, duck, sink" and dyfan "to dip, submerge" (weak, transitive), related to → deep.

Quté is possibly Pers., since Farhang-e Asadai records it with "t" and not Ar. "tayn" (Dehxoda), although its etymology is not established. We propose ultimately from Proto-Ir. *ui-pat-, from *pat- "to fall, to fly," to which is related Pers. oft-, oftâdan "to → fall;" cf. Pashto. qupah "a dip, a dive, a plunge."

(v.intr.) To move, or extend in different directions from a common point.
Math.: Of a sequence or series, to have no unique limit.

M.L. divergere, from → di- "apart," variant of → dis- + vergere "to bend, turn, incline," from PIE *werg- "to turn," from base *wer- "to turn, bend" (cf. L. vertere "to turn," Av. varət- "to turn," Mod.Pers. gard, gardidan "to turn," Skt. vartate "turns round, rolls," Gk. rhatane "stirrer, ladle," Ger. werden, O.E. weorðan "to become."

Verâyidan, from vâ- "apart," → de-, + gerâyidan "to incline toward; to intend; to make for," infinitive of gerâ, the etymology of which is not clear. Gerâ may be a variant of Mod.Pers. kil "bent, inclined" (k/g and l/r interchanges), from PIE base *klei- "to lean, incline," cognate with L. clinare "to bend" (E. declination, inclination, etc.), Gk. klinein "to cause to slope, slant, incline," Skt. sri- "to lean," O.Pers. θray-, Av. sray- "to lean," P.Gmc. *khlinen (Ger. lehnen, E. lean).

1) The act, fact, or amount of diverging.
2) Math.: A differential → operator that, for a three-dimensional vector function F(x,y,z), is the sum of the → scalar products of the unit vectors and the partial derivatives in each of the three component directions. It is written as div F or ∇ . F = (∂F/∂x)i + (∂F/∂y)j + (∂F/∂z)k, ∇ being the → del operator or → nabla. The divergence of a vector field is a → scalar field. In physics, this operator is used to derive the amount of flux per unit volume leaving an infinitesimal element of volume at a point in a vector field. For example, in an electrostatic field, the divergence of the field is zero unless the volume element contains an electric charge.

From diverge, → diverge, + -ence a noun suffix.

Vâgerâyi, from vâgerâ stem of vâgerâyidan, → diverge, + noun suffix -i.

Same as → Gauss's theorem.

→ divergence; → theorem.

Relating to or causing divergence. Gowing away in different directions from a common point or path.
Math.: Failing to approach a limit.

M.L. divergent-, stem of divergens pr.p. of divergere, from → di- "apart," variant of → dis- + vergere "to bend, turn, incline," from PIE *werg- "to turn," from base *wer- "to turn, bend" (cf. L. vertere "to turn," Av. var ət- "to turn," Mod.Pers. gard, gardidan "to turn," Skt. vartate "turns round, rolls," Gk. rhatane "stirrer, ladle," Ger. werden, O.E. weorðan "to become."

Vâgerâ, agent noun from vâgerâyidan, → diverge + noun suffix -i.

A lens which causes a parallel beam of light passing through it to diverge or spread out; concave lens. Same as diverging lens and → negative lens.

→ divergent; → lens.

1) Differing from one another.
2) Composed of various kinds or forms; multiform.

M.E., from L. diversus, p.p. of divertere "to divert," from → di- + vert, from vertere "to turn," → convert.

Gunâgun, literally "of different kinds, sorts, species," from gun "kind, species, sort."

The state or fact of being diverse; difference; unlikeness.

→ diverse; → -ity.

A number which is to be divided by another number (→ divisor). Example: 36 in the expression 36 : 9 = 4.

From L. dividendum "thing to be divided," → division.

Bâxši, from bâxš, → division.

1) The act or process of dividing; state of being divided.
Math.: An operation in which a dividend is divided by a divisor to give a quotient and a remainder.
2) Something that marks a division; a separation.

From O.Fr. division, from L. divisionem (nom. divisio), from divid-, stem of dividere "to cleave, distribute," from → dis- "apart" + -videre "to separate," from PIE base *widh- "to separate."

1) Baxš "portion, part, division," baxšidan "to divide, distribute, grant;" Mod./Mid.Pers. baxt "fortune, fate," baxtan, baxšidan "to distribute, divide," bâq "garden," initially "piece or patch of land," baq "god, lord;" Av. bag- "to attribute, allot, distribute," baxš- "to apportion, divide, give to," baxta- "what is allotted (luck, fortune)," baxədra- "part, portion," baγa- "master, god;" O.Pers. bāji- "tribute, tax;" cf. Skt. bhaj- "to share, divide, distribute, apportion," bhájati "divides," bhakta- "allotted; occupied with; a share; food or a meal, time of eating?" pitu-bháj- "enjoying food;" Gk. phagein"to eat (to have a share of food)"; PIE base *bhag- "to share out, apportion."
2) Šekâf "a fissure, crack, slit," šekâftan "to divide into two long strips, split, break," Mid.Pers. škâftan.

A symbol placed between two quantities (dividend and the divisor) to indicate the division of the first by the second. The division sign is written as a horizontal line with dot above and dot below, ÷ (→ obelus), or a slash or horizontal line.

→ division; → sign.

A number by which another number, the → dividend, is divided.

→ division; → -or.

Baxšyâb, literally "division finder, ~ obtainer," from baxš, → division, + yâb, → finder.

1a) The legal dissolution of a marriage by a court or other competent body.
1b) A legal decree dissolving a marriage.
2) Legally dissolve one's marriage with someone (OxfordDictionaries.com).

M.E., from O.Fr. divorce from L. divortium "separation, dissolution of marriage," from divertere "to turn in different directions, to separate," from di- blended with → de- "apart," + vertere "to turn," → version.

Vosin, from Sangesari vovsin "divorce," related to Mid.Pers. visastan "to break," Mod.Pers. gosastan, ultimately from Proto-Ir. (+ *ui-) *said- "to break, split;" cf. Av. (+ *aua-) auua.siδ- "to split;" Baluci sist/sid-, sind- "to break, split;" Skt. ched "to split, to cut off;" Gk. sizo "to cut through, to split;" L. scindo "I tear up."

A → white dwarf whose spectrum shows strong lines of singly ionized helium He II; He I or H may be present. As a DO star cools, the He II will recombine with free electrons to form He I, eventually changing the DO type into a DB white dwarf.

D short for → dwarf; O a convention; → white.

1) A written or printed paper furnishing information or evidence, as a passport, deed, bill of sale, or bill of lading; a legal or official paper.
2) To furnish with documents. To furnish with references, citations, etc., in support of statements made (Dictionary.com).

M.E., from O.Fr. document "written evidence," from L. documentum "example, proof, lesson," in M.L. "official written instrument," from docere "to show, teach," cognate with Av. daē- "to show," Pers. andišidan, → think.

Dapé, from Mid.Pers. dib, dip "document;" O.Pers. dipī- "inscription;" related to dabir, → secretary; dapidan, infinitive from dap, dapé.

1) Pertaining to, consisting of, or derived from documents.
2) Movies, Television: Based on or re-creating an actual event, era, life story, etc., that purports to be factually accurate and contains no fictional elements (Dictionary.com).

→ document; → -ary.

1) The use of documentary evidence.
2) A furnishing with documents, as to substantiate a claim or the data in a book or article.
3) Computers: Manuals, listings, diagrams, and other hard- or soft-copy written and graphic materials that describe the use, operation, maintenance, or design of software or hardware (Dictionary.com).

→ document; → -tion.