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

An arrangement of the various electrical energy sources with interconnected electrical devices.

→ electric; → network.

The work done by a thermodynamic system as it expands against its surrounding environment. It is equal to ∫pdV, where p is the applied external pressure and V the volume, integrated from the initial V₁ to final V₂.

→ external; → work.

A follow-up community network concerned with → gamma-ray burst (GRB)s. It deals with: 1) locations of GRBs and other → transients detected by spacecraft (most in real-time while the GRB is still bursting), and 2) reports of follow-up observations (the Circulars) made by ground-based and space-based optical, radio, X-ray, TeV, and other observers. The GCN Circulars allow the GRB follow-up community to make optimum use of its limited resources (labor and telescope time) by communicating what has already been done or will soon be done.

→ gamma ray; → coordinate; → network.

Work done in separating the molecules of a system against their forces of attraction. Its value is zero for an → ideal gas.

→ internal; → work.

Any net-like combination of elements in a system; an interconnection of several communicating entities.

O.E. net "mesh," from P.Gmc. *natjan (cf. Du. net, Swed. nät, O.H.G. nezzi, Ger. Netz, Goth. nati "net"), originally "something knotted," from PIE *ned- "to twist, knot" (cf. L. nodus "knot;" Skt. nahyati "binds, ties") + → work.

Turbast literally "joined, tied by a net," from tur "net, fishing net, snare," related to târ "thread, warp, string," tâl "thread" (Borujerdi dialect), tân "thread, warp of a web," from tanidan, tan- "to spin, twist, weave" (Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to stretch, extend;" tanoti "stretches," tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch") + bast "joined, tied," from bastan, vastan "to bind, shut" (O.Pers./Av. band- "to bind, fetter," banda- "band, tie" (cf. Skt. bandh- "to bind, tie, fasten;" PIE *bhendh- "to bind;" Ger. binden; E. bind).

An astronomical → asterism in the constellation → Orion forming an almost vertical line beneath → Orion's Belt. From north to south, the most prominent objects in the Sword are the cluster NGC 1981, the star → 42 Orionis, the famous → Orion Nebula, and the Sword's brightest star → Iota Orionis (→ Hatsya). None of these objects is particularly bright in itself, but their proximity to one another and the nebulosity across much of this region makes the Sword stand out clearly in the night sky.

→ Orion; → sword.

An arbitrary string of characters chosen by a user or system administrator and used to authenticate the user when he attempts to log on, in order to prevent unauthorised access to his account (foldoc.org).

Pass, → passage; → word.

Computers: A very commonly used word that is normally excluded by computer search engines. Stopwords have very little informational content, such as: and, the, of, it, as, may, that, a, an, of, off, etc.

→ stop; → word.

Rahâ-vâž, literally "free word," from rahâ "free, set free" (O.Pers. rad- "to leave," Skt. rah-, rahati "separates, leaves," Av. razah- "isolation;" PIE *redh-) + vâž, vâžé, → word. Fekan-vâž, literally "dropped word," from fekan present stem of fekandan, afkandan "to throw, cast away;" Mid.Pers. abgandan "to throw;" O.Pers. avakan- "to throw, place on," from Proto-Iranian *kan- "to throw, place, put."

1) A weapon having various forms but consisting typically of a long, straight or slightly curved blade, sharp-edged on one or both sides, with one end pointed and the other fixed in a hilt or handle (Dictionary.com).
2) → Orion's Sword.

M.E.; O.E. sweord; cognate with Du. zwaard, Ger. Schwert, Sw. svärd.

Šamšir, Mid.Pers. šamšêr / šamšyl, Parthian safsêr; cf. Gk. sampsera denoting a "foreign sword." The E. scimitar derives ultimately from šamšir through M.Fr. cimeterre or directly from It. scimitarra, possibly from an unknown Ottoman Turkish word, borrowed from Pers.

In → analytical mechanics, an element of work performed in a → virtual displacement by the → forces acting on all n particles of a → holonomic system with s degrees of freedom (→ degree of freedom).

→ virtual; → work.

In → analytical mechanics, a principle whereby it is necessary and sufficient for the equilibrium of any material system with ideal constraints that the sum of the elements of work, performed by the applied forces acting on the system in any virtual displacement, be equal to zero (if all constraints are bilateral) or less than zero (if some of the constraints are unilateral).

→ virtual; → work; → principle.

A unit of language, consisting of one or more sounds or their written representation, that communicates a meaning. → stopword

M.E., from O.E. word; cf. Du. woord, O.H.G., Ger. wort, Goth. waurd; related to verb, from L. verbum "verb;" from PIE *wer- "to speak, say."

Vâžé "word;" Mid.Pers. vâc, vâcak "word, speech;" related to âva "voice, sound," âvâz "voice, sound, song," bâng "voice, sound, clamour" (Mid.Pers. vâng); Av. vacah- "word," vaocanghê "to decalre" (by means of speech), from vac- "to speak, say;" cf. Skt. vakti "speaks, says," vacas- "word;" Gk. epos "word;" L. vox "voice;" PIE base *wek- "to speak."

If a force F acting on a body moves its point of application through a distance r, the work is defined by the product F.r.cosθ, where θ is the angle between the line of action of the force and the displacement. Work can be positive, negative, or zero.

M.E.; O.E. weorc, worc "something done, action, military fortification," from P.Gmc. *werkan (cf. O.S., O.Fris., Du. werk, O.N. verk, O.H.G. werah, Ger. Werk), from PIE base *werg- "to work;" cognate with Pers. varz-, varzidan "to labor, practise," → erg.

Kâr "work," Mid.Pers kâr; Mod./Mid.Pers. kardan "to do, to work," Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build," Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base k^wer- "to do, to make."

The least amount of energy required to remove an electron from the surface of a solid, to a point just outside the solid where the electron has zero kinetic energy. See also → photoelectric effect.

→ work; → function.

The → work of the resultant force exerted on a particle equals the change in kinetic energy of the particle.

→ work; → energy; → principle.

A group of people working together to achieve a stated goal.

→ work; → -ing; → group.

The double shock structure formed in any two fluids that collide supersonically. A working surface consists of two → shocks, a → bow shock where the ambient material is shocked and accelerated, and a jet shock or → Mach disk, where the → jet material is decelerated. It is common to find multiple working surfaces along the axis of an → Herbig-Haro jet, testifying to recurrent eruptions of the underlying source.

→ work; → -ing; → surface.

1) A place where manual work is done, especially manufacturing or repairing.
2) A group of people working on a creative project, discussing a topic, or studying a subject.

→ work + shop M.E. shoppe, O.E. sceoppa; cf. O.H.G. scopf "porch," Ger. Schuppen "a shed").

Kârgâh "workshop," from kâr, → work, + gâh "place; time" (Mid.Pers. gâh, gâs "time;" O.Pers. gāθu-; Av. gātav-, gātu- "place, throne, spot;" cf. Skt. gâtu- "going, motion; free space for moving; place of abode;" PIE *gwem- "to go, come").

1) The Earth with its inhabitants. Compare → cosmos and → Universe.
2) Other planets, particularly → exoplanets.
3) Any realm, or domain, with all pertaining to it.
4) Physics: The → space-time in four dimensions, as distinguished from three-dimensional space. → world line.

M.E.; O.E. woruld, weorold; cf. O.S. werold, O.Fris. warld, Du. wereld, O.N. verold, O.H.G. weralt, Ger. Welt.

Jahân, variants keyhân, geyhân "world," giti "world, material world, time;" Mid.Pers. gêhân "world," gêtig "the material world; wordly," Manichean Mid.Pers. gyh "world," gyh'n "worlds;" Av. gaēθā- "being, world, matter, mankind" (O.Pers. gaiθā- "livestock"), gaya- "life, manner of living," root gay- "to live" (present tense jiva-), cognate with Skt. jīv- "to live," jīva- "alive, living;" Gk. bios "life," L. vivus "living, alive," vita "life;" PIE base *g^wei- "to live" (cf. O.E. cwic "alive;" O.C.S. zivo "to live;" Lith. gyvas "living, alive;" O.Ir. bethu "life," bith "age, life, world;" Welsh byd "world"). The Pers. words zistan "to live," zendé "alive," zendegi "life," and jân "vital spirit, soul; mind" belong to this family.

In relativity, the path traced out in four-dimensional → space-time that represents a continuous sequence of events relating to a given particle. A point on a world line is called an → event. Any straight world line corresponds to an → inertial motion. Curved world lines represent → accelerated motion. A world line that curves corresponds to an accelerated observer. World lines are shown on space-time diagrams.

→ world; → line.