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

Diverge or deviate from the straight path; produce → aberration.

Aberrate, from aberrare "go astray," from ab- "away" + errare "to wander."

Birâhidan, from birâh "a devious path; a wanderer, who deviates, errs," from bi- "without" + râh "way".

1) An imperfection in the imaging properties of a → lens or → mirror. The main aberrations are → chromatic aberration, → spherical aberration, → coma, → astigmatism, → distortion, and → field curvature.
2) → aberration of starlight.
See also: → aberration angle→ aberration constan→ aberration of starlight→ aberration orbit→ annual aberration→ chromatic aberration→ constant of aberration→ diurnal aberration→ optical aberration→ planetary aberration→ relativistic aberration→ secular aberration→ spherical aberration→ stellar aberration.

Aberration, from L. aberrationem, from aberrare "go astray," → aberrate.

Birâheš, from birâidan, → aberrate.

The angle tilt required by the → stellar aberration phenomenon in order that a moving telescope points directly to a star.

→ aberration; → angle.

Same as → constant of aberration.

→ aberration; → constant.

→ aberration of starlight

→ aberration; → light.

An apparent displacement in the observed position of a star. It is a result of the finite speed of light combined with the relative motion of the Earth through space. Suppose that you walk through a vertically falling rain with an umbrella over your head. The faster you walk, the further you must lower the umbrella in front of yourself to prevent the rain from striking your face. For starlight to enter a telescope, a similar phenomenon must occur, because the Earth is in motion. The telescope must be tilted in the direction of motion by an angle: tan θ =(v/c), where v the Earth velocity and c the speed of light. The aberration of starlight was discovered by the English astronomer James Bradley (1693-1762) in 1729 by observing → Gamma Draconis. The tilt angle is θ = 20''.50, from which the Earth's orbital speed, 29.80 km s^-1, can be deduced, using the above equation. See also → annual aberration; → diurnal aberration; → secular aberration. → Special relativity modifies the classical formula for aberration, predicting results which differ substantially from those of classical physics for objects moving at a substantial fraction of the speed of light; → relativistic aberration.

→ aberration; → star; → light.

The apparent path described by a star on the → celestial sphere due → annual aberration. A star at the → ecliptic pole is seen to move around a circle of angular radius about 20".50, once a year. A star on the → ecliptic oscillates to and fro along a line of angular half-length 20".50. At an intermediate → celestial latitude, β, the aberration orbit is an ellipse, with semi-major axis 20".50 and semi-minor axis (20".50) sin β.

→ aberration; → orbit.

Of or pertaining to → aberration.

→ aberration; → -al.

A → Besselian day number denoted by C or D.

→ aberration; → -al; → day; → number.

The → locus of points on the → celestial sphere occupied by a star during the annual → revolution of the → Earth about the → Sun due to → annual aberration. annual aberration.

→ aberrational; → ellipse.

The → erosion of a surface through a process such as → vaporization or → friction.

L. ablatio, ablation, from ablatus, from ab- "away" + latus "carried."

Farsâb from far-, prefix denoting "abundance, excess" + sâb present stem of sâbidan "to rub, wear out," variants sâyidan, pasâvidan "to touch," Khotanese sauy- "to rub," Sogdian ps'w- "to touch," Proto-Iranian *sau- "to rub."

Not typical, usual, or regular; not normal; deviant. → anomalous, → anomaly.

M.L. anormalis, blend of L.L. abnormis "deviating from a rule," from ab- "off, away from" + L. norma "rule."

Bihanjâr, from Pers. bi- "without" + Pers. hanjâr "rule, habit, law, staright road."

1) To terminate a procedure before it has finished naturally.
2) In computer science, to terminate an application intentionally or unexpectedly. For example, to stop a search or a print job; or unexpected termination of a program because of bugs or difficulties.

From L. abortus, p.p. of aboriri "to miscarry" (a child) from → ab- "from, away, off," + oriri "to rise, be born;" cf. Pers. rasidan "to attain; to arrive" (Mid.Pers. rasidan "to arrive, to mature;" O.Pers./Av. rasa- present stem of ar- "to move, go or come toward;" Skt. ar-, rcchati "reaches;" Gk. erkhomai "to go, to reach").

Fagânidan, from fagâné "abortion", related to fegandan, fekandan, afkandan "to throw, to cast away;" Mid.Pers. abgandan "to throw;" O.Pers. avakan- "to throw, place on," from Proto-Iranian *kan- "to throw, place, put."

The stopping of a process; a result of such termination.

Verbal noun of → abort.

In plane Cartesian coordinates, the distance of any point from the vertical axis (y-axis). The distance from the horizontal axis (x-axis) is called → ordinate.

From L abscissa (linea) "(a line) cut off," from p.p. of abscindere "to cut off," from → ab- "off, away" + scindere "to cut." The word abscissa was first used by Stefano degli Angeli (1623-1697), a professor of mathematics in Rome.

Pirâ, present stem of pirâstan "to prune, clip, trim; to adorn, embellish (especially by cutting, clipping, or taking away)," related to ârâstan "to arrange, adorn," from Mid.Pers. payrâstan, patrâstan "to arrange, adorn," ultimately from Proto-Iranian *pati-rad-. The first component *pati- "to, toward, near to, against;" cf. Mid.Pers. pât-, from O.Pers. paity "against, back, opposite to, toward, face to face, in front of;" Av. paiti; Skt. práti "toward, against, again, back, in return, opposite;" Pali pati-; Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti. The second component *rad- "to direct, to prepare;" cf. O.Pers. rād- "to prepare," rās- "to be right, straight, true," rāsta- "straight, true" (Mod.Pers. râst "straight, true"); Av. rāz- "to direct, put in line, set," razan- "order;" Gk. oregein "to stretch out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Skt. rji- "to make straight or right, arrange, decorate;" PIE base *reg- "move in a straight line."

1) State of being away or not being present.
2) Lack; deficiency.

Noun from → absent.

1) Not in a certain place at a given time; away, missing (opposed to present).
2) Lacking; nonexistent (Dictionary.com).

M.E., from M.Fr. absent, from L. absentem (nominative absens), p.p. of abesse "to be away from," from → ab- "away" + esse "to be," → present.

Apâst, on the model of L. absentem, as above, from apâ- "away from," → apo-, + ast "is," → present.

A person who is absent, especially from work or school (Dictionary.com).

From → absent + -ee a suffix forming nouns that denote a person who is the object or beneficiary of the act specified by the verb, from Fr. -é, ending of p.p.s used as nouns.

Apâstgar, from apâst, → absent, + -gar, → -or.

Voluntary non attendance at work, without valid reason. Absenteeism means either habitual evasion of work, or willful absence as in a strike action. It does not include involuntary or occasional absence due to valid causes, or reasons beyond one's control, such as accidents or sickness (BusinessDictionary.com).

→ absent; → -ism.

1) General: Not limited by restrictions or exceptions; perfect in quality or nature; unqualified in extent or degree; complete.
2) Physics: Relating to measurements or units of measurement derived from fundamental units of length, mass, and time.
3) Physics: Having an ideal value as opposed to a conditional or relative one.
See also: → absolute acceleration, → absolute dating, → absolute humidity, → absolute luminosity, → absolute magnitude, → absolute permeability, → absolute space, → absolute temperature, → absolute tensor, → absolute time, → absolute viscosity, → absolute zero.

From M.Fr. absolut, from L. absolutus "unrestricted," p.p. of absolvere "to set free," from ab- "away" + solvere "to loosen," from PIE *leu-. → solve.

Avast from negation prefix → a- + vast, variant of bast, basté "tied, bound," from Mid.Pers. bastan/vastan "to bind, shut," Av./O.Pers. band- "to bind, fetter," banda- "band, tie," Skt. bandh- "to bind, tie, fasten," PIE *bhendh- "to bind," cf. Ger. binden, E. bind, → band.

Synonymous: motalq(مطلق), from Ar.