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

A space project, initially → LISA, consisting of a configuration of three satellites, aimed to detect low frequency → gravitational waves that cannot be measured by ground-based detectors. The detection range will be from about 0.1 milliHz to 1 Hz. One "mother" and two "daughter" spacecrafts will be brought into an orbit around the Sun, which is similar to the Earth's orbit. The satellites will fly in a near-equilateral triangle formation, with a constant distance of one million km between, following the Earth along its orbit at a distance of around 50 million km. The mother spacecrafts carries two and each of the daughter spacecraft carry one free-flying → test masses that will be kept as far as possible free of external disturbances. The mutual distances of the test masses from satellite to satellite will be measured by means of high-precision, → Michelson-like laser → interferometry. In this way, the extremely small distance variations between the test masses of two satellites can be detected which are caused by the passages of a gravitational waves. The required measurement accuracy of the distances amounts to typically 1/100 of the diameter of a hydrogen atom (10^-12 m) at a distance of two million km.

→ evolve; → laser; → interferometer; → space; → antenna.

A star that has left the → main sequence.

→ evolve; → star.

A female sheep, especially when fully mature.

M.E.; O.E. eowu, ewe "female sheep;" cognate with O.H.G. ou, ouwi, Du. ooi, L. ovis, Gk. ois, ois, Skt. avi; PIE *owi- "sheep."

Miš, from Mid.Pers. mêš "sheep, ewe;" Av. maeša- "sheep, ewe;" cf. Skt. mesa-, mesi "sheep, ewe."

A classical → T Tauri star, and the EXor prototype, subject to sporadic outbursts. It remains at about V = 13.2 mag for extended periods to brighten to as much as V = 8.4 mag (1955-1956). When EX Lupi is at minimum, it resembles a classical T Tauri star of type M0. At outburst this spectrum is veiled by a hot continuum, the equivalent widths of the optical-region emission lines decrease, and reverse P Cygni absorption components appear at the higher Balmer lines. The outbursts are believed to be due to episodic infall onto the M0 star. → FU Orionis objects.

E and X, letters of alphabet; Lupi, genitive of → Lupus.

Prefix meaning "out of, outside; from," but also "upwards, completely, deprive of, without."

From M.E., from O.Fr., from L. ex- "out of, from," akin to Gk. ex, ek "out of;" Av. uz-, us-, see below; from PIE base *eghs "out" (cf. Gaul. ex-; O.Ir. ess-; O.C.S. izu; Rus. iz).

Pers. os- (variants zo-, so-), from Mid.Pers. us-, uz-; Av. uz-, us- "out of, outside, from;" O.Pers. ud- (ud-apatatā "to rise up, rebel"), also Pers. preposition az "from; of; out of," prefixes zo- (in zodudan "to polish, clean;" Mid.Pers. uzdâtan; Av. uzdā-, from uz- + dā- "to make, create"), âz- (âzmâyeš, → experiment), haz- (haziné "cost, expenditure;" Mid.Pers. uzên, uzênak, from *uz-ayana- "going out;" Av. us- + ay- "to go," → assembly), es- (eskane "chisel"); PIE *ud- "up, out," cf. Skt. úd "up, away, out;" O.E. ūt "out;" E. out; O.H.G. ūz "out;" Ger. aus; Russ. vy- "out."
Borun "out, the outside" (Mid.Pers. bêron, from bê "outside, out, away" + rôn "side, direction;" Av. ravan- "(course of a) river").

A prefix in the SI system of units denoting 10¹⁸.

Adopted in 1991, from Gk. ex "six," because it is equal to (1000)⁶.

1) Strictly accurate or correct; precise, as opposed to approximate.
2) The complete solution of an equation. For example, in the equation x² = 7, the positive solution 2.646 is correct to three decimal places. The exact answer is x = 7^1/2.
See also:
→ exact differential, → exact differential equation, → exact science, → accurate, → precise, → rigorous.

From L. exactus, p.p. of exigere, literally "to drive out, thrust out," also "demand, finish, measure," from → ex- "out" + agere "drive, lead, act," → act.

Razin "firm, solid, strong" [Dehxodâ, Steingass], Mid.Pers. razên "firm, strong, secure, solid."

If N(x,y) is a → function of two → independent variables, then dN = (∂N/∂x)dx + (∂N/∂y)dy is the exact differential.

→ exact; → differential.

A → differential equation composed of → continuous  → differentiable functions for which certain conditions are fulfilled. The equation M(x,y)dx + N(x,y)dy = 0 is called exact if M(x,y) and N(x,y) are continuous differentiable functions for which the following relationship is fulfilled: ∂M/∂y = ∂N/∂x, and ∂M/∂y and ∂N/∂x are continuous in some region.

→ exact; → differential; → equation.

A value that is known with complete certainty. Examples of exact numbers are defined numbers, results of counts, certain unit conversions. Some examples: there are exactly 100 centimeters in 1 meter, a full circle is exactly 360°, and the number of students in a class can exactly be 25.

→ exact; → number.

A field of study that admits especially precise predictions and rigorous methods of testing hypotheses, especially reproducible experiments involving quantifiable predictions and measurements.

→ exact; → science.

1) The act of examining; inspection; inquiry; investigation.
2) The state of being examined.
3) The act or process of testing pupils, candidates, etc., as by questions (Dictionary.com).

Noun from → examine.

1) To inspect or scrutinize carefully.
2) To inquire into or investigate.
3) To test the knowledge, reactions, or qualifications of (a pupil, candidate, etc.), as by questions or assigning tasks (Dictionary.com).

M.E., from M.Fr. examiner "interrogate, question," from L. examinare "to test or try; consider," literally "to weigh," from examen "a means of weighing or testing," probably ultimately from exigere "weigh accurately," → exact.

Barrasidan, from bar- "up; upon; on; in; into; at; forth; with; near; before; according to," → on-, + rasidan "to attain; to arrive," → access.

One of a number of things, or a part of something, taken to show the character of the whole.

From O.Fr. essample, from L. exemplum "a sample," literally "that which is taken out," from eximere "to take out, remove," from → ex- + emere "to obtain, buy," originally "to take," from PIE base *em- "to take" (cf. Av. yam-, yās- "to hold, take hold of," apayeiti (with apa) "taking away a thing from;" O.Pers. āyasa- "to take as one's own;" Skt. yam- "to hold, sustain," yamati "holds, subdues;" O.C.S. imo "to take;" Lith. imti, ima, émé "to take").

Nemuné, from nemun "index; guide," from nemudan "to show, display," from Mid.Pers. nimūdan, from ne- "down; into;" O.Pers./Av. ni- "down; below; into," → ni-, + mun, Av. māy- "to measure," → display.

Possessing outstanding quality or superior merit; remarkably good (Dictionary.com).

M.E., from O.Fr. excellent "outstanding," from L. excellentem (nominative excellens) "towering, prominent, superior," pr.p. of excellere "to surpass, be superior,"from → ex- "out from" + cellere "to rise high, tower," related to celsus "high, great," from PIE root *kel- "to be elevated; hill;" from which are derived L. collis "hill," columna "projecting object," culmen "top, summit," cellere "raise;" Gk. kolonos "hill," kolophon "summit;" Lithuanian kalnas "mountain," kalnelis "hill;" E. hill; Pers. dialects (Gilân) kol, kulâ "hill," (Dâmqân) kalut, kolut "successive soil hills, hill," (Tabari) keti "hill," (Jâsk) kit "hill."

Mid.Pers. pahrom "excellent," variant pahlom, ultimately from *parθama- "the highest, the most elevated," literally "Parthian," adj. from Parθa(va)-; cf. pahlavân "hero," another similar respect word related to Parthia (Nyberg 1974).

The center of an → excircle.

→ ex-; → center.

1) With the exclusion of; excluding.
2) To exclude; leave out.

From M.Fr. excepter , from L. exceptus, p.p. of excipere  "to take out," from → ex- "out" + capere "to take," → concept.

Sogert, from so-, variants zo- and os-, → ex- "out," + gert- "to take," → concept; cf. Mid.Pers. Parthian zgirw- "to take out," from uz- "ex-" + girw- "to take."

1) The act of excepting or the fact of being excepted.
2) Something excepted. 

Verbal noun of → except.

Forming an exception; not ordinary.

→ exception; → -al.

The state or an instance of surpassing usual, proper, or specified limits. → color excess; → infrared excess.

From L. excessus "going beyond bounds," from stem of excedere "to go beyond," from → ex- "out" + cedere "to go, yield;" cf. Gk. hodos "way;" PIE base *ked- "to go, yield."

Fozuni, from afzuni "excess," afzuni kardan "to exceed bounds," from afzudan "to add, increase," from Mid.Pers. abzudan "to increase, grow;" O.Pers. abijav- "to increase, add to, promote," from abi-, aiby- "in addition to; to; against" + root jav- "press forward;" Av. gav- "to hasten, drive;" Sk. jav- "to press forward, impel quickly, excite," javate "hastens."
Ferehbud "excess" (Mid.Pers. frehbūd "excess"), from Mod.Pers. fereh, firih "much; more" + bud "to be." The first component fereh, from Mid.Pers. frây "more, much," from Av. frāyah- "more; too much, very much" (frāyô.humata- "rich in good thoughts"). The second component bud, budan "to be," from Mid.Pers. budan, from O.Pers./Av. bav- "to be; become, take place;" Av. buta- perf. ptcpl. pass., bavaiti "becomes" (cf. Skt. bhavati "becomes, happens," bhavah "becoming; condition, state;" PIE *bheu- "to be, come into being, become;" Gk. phu- "become," phuein "to bring forth, make grow;" L. fui "I was" (perf. tense of esse), futurus "that is to be, future;" Ger. present first and second person sing. bin, bist; E. to be; O.Ir. bi'u "I am;" Lith. bu'ti "to be;" Rus. byt' "to be").