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

The multi-layered, light-sensitive membrane lining the inside of the posterior wall of the eyeball. It contains the rods and cones that receive an image from the lens and send it to the brain through the optic nerve.

M.L. retina, from L. rete "net," Gerard of Cremona's 12c. translation of Arabic (tabaqa) shabakiyya "net-like (layer)," itself a translation of Gk. amphiblestron used by the famous Greek physician, surgeon, and philosopher Galen (AD c129-c216). This term had two meanings, "a surrounding coat" (of the vitreous) and "a fisherman's net." Galen used the word in the first sense, but when it was translated into Ar. the translator inappropriately chose the second meaning.

Šabakiyé, from Ar. šabakiya, from šabaka, šabakat "a net."

An old galaxy with faint emission lines whose ratios are similar to those of → LINERs, i.e. galaxies with low-ionization nuclear emission-line regions. All galaxies after consuming their → molecular clouds, where stars are formed, follow a "passive" evolution during which their → stellar populations simply get older and older. The old stellar populations contain hot post-→ AGB stars and → white dwarfs which are able to ionize the surrounding gas and produce spectra identical to those of LINERS.

Retired in the sense "withdrawn from or no longer occupied with one's business or profession," p.p. of retire, from M.Fr. retirer "to withdraw (something)," from → re- "back" + O.Fr. tirer "to draw;" → galaxy. The concept of retired galaxies was first proposed by G. Stasińska et al. (2008, MNRAS 391, L29) to name the final stages of galaxies that cease their star forming activity. The word "retired" is also to be taken by opposition to "active" in the sense of "containing an accreting black hole" (like Seyfert galaxies), since liners are often thought to be a scaled down version of Seyfert nuclei.

Bâznešasté "retired," literally "seated back, seated away," from bâz-→ re- + nešasté "seated," p.p. of nešastan "to sit;" Mid.Pers. nišastan "to sit;" O.Pers. nišādayam [1 sg.impf.caus.act.] "to sit down, to establish," hadiš- "abode;" Av. nišasiiā [1 sg.subj.acr.] "I shall sit down," from nihad- "to sit down," from ni- "down, in, into," → ni-, + had- "to sit;" PIE base *sed- "to sit;" cf. Skt. sad- "to sit," sidati "sits;" Gk. hezomai "to sit," hedra "seat, chair;" L. sedere "to sit;" O.Ir. suide "seat, sitting;" Welsh sedd "seat;" Lith. sedmi "to sit;" Rus. sad "garden;" Goth. sitan, Ger. sitzen; E. sit.

1a) The forced or strategic withdrawal of an army or an armed force before an enemy, or the withdrawing of a naval force from action.
1b) The act of withdrawing, as into safety or privacy; retirement; seclusion.
2) To withdraw, retire, or draw back, especially for shelter or seclusion.

Mi.E. retret, from O.Fr., variant of retrait, noun use of p.p. of retraire "to draw back," from L. retrahere, from → re- + trahere "to draw."

Pas-kešidan "to retreat, pull back," from pas, → back, + kašidan "to pull, to draw, to drag," → galaxy.

Moving backward; having a backward motion or direction. → retrograde motion.

M.E., from L. retrogradus "going backward," from retrogradi "move backward," from retro- "backward" + gradi "to go, step."

Pasrow, pasraft, from pas- "back, behind," → back, + row, raft present and past stems of raftan "to go, walk;" (Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack").

The orbital motion or rotation of a solar system body in a clockwise direction (East to West) when viewed from the north pole of the ecliptic. It is a motion opposed to the → direct motion of the great majority of solar system bodies.

→ retrograde; → motion.

An object which has a retrograde orbit around its primary.

→ retrograde; → object.

An orbit with an inclination between 90° and 270° such as those of some comets and small asteroids orbiting the Sun.

→ retrograde; → orbit.

A shape of constant width created using an equilateral triangle and three similar circles. The equilateral triangle lies in the first circle with a vertex coinciding with the center of the circle and the sides equal to the circle radius. The centers of the two other circles are located at the two other vertices. The Reuleaux triangle is the intersection of the three circles.

Named after Franz Reuleaux (1829-1905), a German engineer, specialist of analysis and design of mechines; → triangle.

An act or instance of reversing. The state of being reversed. → phase reversal.

From → reverse + → -al.

Opposite or contrary in position, direction, order, etc.
Acting in a manner opposite or contrary to that which is usual. → invert = vârun (وارون).

M.E. revers from O.Fr. revers "reverse, cross," from L. reversus, p.p. of revertere "to turn back," from → re- "back" + vertere "to turn," cognate with Pers. gard "to turn," as below.

Vârun "inverse, upside down," from vâ- "back, backward, again, re-," variant of bâz-, from Mid.Pers. abâz-, apâc-, O.Pers. apa- [pref.] "away, from;" Av. apa- [pref.] "away, from," apaš [adv.] "toward the back;" cf. Skt. ápāñc "situated behind."
Vâgard, from vâ-, → re-, + gard present stem of gardidan, gaštan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" cf. Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend").

A → shock front in a → supernova remnant (SNR) arising from the interaction of the → supersonic  → forward shock wave with the → interstellar medium (ISM) material. The reverse shock forms as the high pressure gas behind the forward shock wave expands and pushes back on the stellar ejecta. Reverse shock propagates into ejecta, starting from outside.

→ reverse; → shock.

Capable of returning to an original condition. → reversible process.

→ reverse + → -able.

Any physical process which can be performed in the reverse direction, the whole series of changes constituting the process being exactly reversed. → irreversible process.

→ reversible; → process.

A layer of relatively cool gas forming the lower part of the Sun's chromosphere, just above the photosphere, that gives rise to absorption lines in the Sun's spectrum.

Reversing verbal adj. of → reverse; → layer.

1a) A critical article or report.
1b) The process of going over a subject again in study in order to examine and summarize the facts.
2) To discuss a research subject in a critical review; write a critical report upon.

M.E., from O.Fr. reveue "a reviewing, review," from feminine p.p. of revoir "to see again, reexamine," from O.Fr. reveoir, from → re- + veoir, veeir "to see."

Bâzdâ, from bâz-, → re-, + dâ root of didan "to see" (Mid.Pers. ditan "to see, regard, catch sight of, contemplate, experience;" O.Pers. dī- "to see;" Av. dā(y)- "to see," didāti "sees;" cf. Skt. dhī- "to perceive, think, ponder; thought, reflection, meditation," dādhye; Gk. dedorka "have seen") + kardan "to do," → -or.

A talk that deals with a subject by examining, criticizing, and summarizing the facts.

→ review; → talk.

To alter something already written or printed, in order to make corrections, improve, or update (Dictionary.com).

M.E., from M.Fr. reviser, from L. revisere "to look at again, look back on," frequentative of revidere, from → re- "again" + videre "to see," → vision.

Bâznegaristan, from bâz- "again," → re-, + negaristan "to look, observe," → theory.

the act or work of revising. a process of revising. a revised form or version, as of a book.

Verbal noun of → revise.

1) An improvement in the condition, strength, or fortunes of someone or something.
2) A restoration to life or consciousness.
3) An instance of something becoming popular, active, or important again (OxfordDictionaries.com).

→ revive; → -al.

1a) Regain life, consciousness, or strength.
1b) Give new strength or energy to.
2a) Restore to life or consciousness (OxfordDictionaries.com).

Ultimately from L. revivere; → re-; → survive.