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

1a) A shift from one to another.
1b) A device used to break or open an electric circuit or to divert current from one conductor to another.
2) To shift or exchange; To connect, disconnect, or redirect.

Switch "slender riding whip, flexible stick," probably from a Flemish or Low German word akin to Hanoverian swutsche, a variant of Low Ger. zwukse "long thin stick, switch."

Degarbân, from degar "other, another" (Mid.Pers. dit, ditikar "the other, the second;" O.Pers. duvitiya- "second," Av. daibitya-, bitya- "second;" Skt. dvitiya- "second," PIE *duitiio- "second") + -bân a suffix denoting "keeper, guard," sometimes forming agent nouns or indicating relation, → host.

The act of changing one thing or position for another.

Verbal noun of → switch (v.).

A kind of → deductive reasoning whereby from two initial → propositions (two → premises) a third related proposition (→ conclusion) is derived. The typical form of a → categorical syllogism is "A is B;" "C is A;" "Therefore, C is B." For example, "All humans are mortal." "John is human." "Therefore, John is mortal." "Mortal" (B) is called the → major term; it occurs in the first premise and is the → predicate of the conclusion. "John" (C), the subject of the conclusion, is called the → minor term. "Human," which is common to both premises and is excluded from the conclusion, is called the → middle term. See also → Aristotelian forms. Syllogism is purely formal. It does not enrich knowledge, but gives a new presentation to what is already known. It is also possible to have a logically valid syllogism based on → absurd premises. For example, "All cats are mammals." "All cats are animals." "Therefore, all animals are mammals." Syllogism, representing the earliest branch of → formal logic, was developed in its original form by Aristotle in his Organon (Prior Analytics) about 350 BC.
See also: → bivalent logic, → polyvalent logic, → symbolic logic, → propositional logic, → first-order logic, → predicate logic, → syllogistic; → fuzzy logic.

M.E. silogisme, from O.Fr. silogisme, from L. syllogismus, from Gk. syllogismos "a syllogism," originally "inference, conclusion; computation, calculation," from syllogizesthai "bring together before the mind, compute, conclude," from assimilated form of → syn- "together" + logizesthai "to reason, to count," from logos "a reckoning, reason," → logic.

Bâhamšomârik, literally "reckoning together," from bâham "together," from bâ "with," → hypo-, + ham, → syn-, + šomâr present stem of šomârdan "to reckon, calculate, enumerate, account for," → count, + suffix -i.

1a) Of or pertaining to a → syllogism.
1b) Like or consisting of syllogisms.
2a) The part of logic that deals with syllogisms.
2b) Syllogistic reasoning (Dictionary.com).

→ syllogism; → -ic.

Of or pertaining yo symbiosis in biology, denoting a close, prolonged association between two or more different organisms of different species that may be, but does not necessarily, of mutual benefit. → symbiotic star.

From Mod.L., from Gk. symbiosis "a living together," from symbioun "live together," from symbios "(one) living together (with another), partner," from → syn- "together" + bios "life," → bio-.

Hamzi "living together," from ham- "together," → syn-, + zi- present stem of zistan "to live," → bio-.

A → B[e] star whose spectrum shows the presence of a cool component characterized mainly by → TiO bands.

→ symbiotic; → B[e] star.

A stellar object whose optical spectrum displays lines characteristic of gases of two very different temperatures, typically of an M star (3500 K) and a B star (20 000 K) superimposed. A symbiotic star is in fact a close binary system.

→ symbiotic; → star.

1) Something that stands for or represents something else, especially an object representing an abstraction.
2) A conventional sign or character that represents something in a specific context, e.g. an operation or quantity in mathematics or music.

M.E., from L.L. symbolum "creed, token, mark," from Gk. symbolon "sign, mark," from → syn- "together" + stem of ballein "to throw."

Namâd variant of namud, nemud past stem of nemudan "to show;" Mid.Pers. nimūdan, nimây- "to show," from O.Pers./Av. ni- "down; into," → ni- (PIE), + māy- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure."

Of or relating to a symbol or symbols; serving as a symbol.

→ symbol; → -ic.

A modern development of → formal logic based on a system of → symbols and → axiomatics in accordance with precise rules. It uses a formalized → artificial language to avoid the ambiguities and logical inadequacies of → natural languages. Symbolic logics are → polyvalent when they admit → truth values other than → true and → false.

→ symbolic; → logic.

A relation between two quantities such that the first is to the second as the second is to the first. In symbols: a R b = b R a. For example, multiplication is an operation with a symmetric relation between the factors: 5 x 3 = 3 x 5.

→ symmetric; → relation.

A tensor that is → invariant under any → permutation of its indices (→ index). In other words, a tensor that equals its → transpose. For example, a second-order → covariant tensor A_jk if its components satisfy the equality: A_jk = A_kj.

→ symmetric; → tensor.

Characterized by or exhibiting → symmetry.

Adj. of → symmetry.

1) A quality of a geometric figure that has exactly similar parts with respect to a point, a line, or a plane of its own.
2) A geometric transformation that does not alter neither the shape nor the size of a figure.
3) A property of a mathematical function whose value does not change when its variables are interchanged.
4) Of physical phenomena, the property of remaining invariant under certain changes (as of rotation, reflection, inversion in space, the sign of the electric charge, parity, or the direction of time flow). See also → Noether's theorem.
See also:
→ asymmetry, → axial symmetry, → axisymmetry, → baryon asymmetry, → charge-parity symmetry, → dissymmetry, → gauge symmetry, → parity symmetry, → spherical symmetry, → spontaneous symmetry breaking, → supersymmetry, → symmetry group, → T-symmetry.

From L. symmetria, from Gk. symmetria "agreement in dimensions, due proportion, arrangement," from symmetros "having a common measure, even, proportionate," from → syn- "together" + metron "meter;" PIE base *me- "to measure;" cf. O.Pers., Av. mā- "to measure;" Skt. mati "measures;" L. metri "to measure."

Hamâmun from ham-, → syn- "together," + -â- epenthetic vowel + mun, variant mân "measure," as in Pers. terms pirâmun "perimeter," âzmun "test, trial," peymân "measuring, agreement," peymâné "a measure; a cup, bowl," from O.Pers./Av. mā(y)- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure."

A group of symmetry-preserving operations composed of all rigid motions or similarity transformations of some geometric object onto itself.

→ symmetry; → group.

A prefix occurring in loanwords from Gk., having the same function as → co-; used, with the meaning "with, together," in the formation of compound words. Variants sy-, syl-, sym-, sys-.

From Gk. syn "with, together with," of unknown origin.

Ham- "together, with; same, equally, even," Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-.

A line connecting the dust grains in a comet tail that left the nucleus at the same time. → syndyne.

From L. synchronus "simultaneous," from Gk. synchronos "happening at the same time," from → syn- "together" + khronos "time."

Hamzamân, from ham-, → syn- "together" + zamân, → time.

1) Going on at the same rate and exactly together. Compare → simultaneous.
2) Having the same period and phase of oscillation or cyclic movement.

From L. synchronus "simultaneous," from Gk. synchronos "happening at the same time," from → syn- "together" + khronos "time."

Hamgâm literally "at the same pace," from ham-, → syn-, + gâm "step, pace," Mid.Pers. gâm, O.Pers. gam- "to come; to go," Av. gam- "to come; to go," jamaiti "goes," Mod.Pers. âmadan "to come," Skt. gamati "goes," Gk. bainein "to go, walk, step," L. venire "to come," Tocharian A käm- "to come," O.H.G. queman "to come," E. come; PIE root *gwem- "to go, come."

→ synchronous rotation.

→ synchronous; → orbit.

Of a body orbiting another, where the orbiting body takes as long to rotate on its axis as it does to make one orbit. Therefore it always keeps the same hemisphere pointed at the body it is orbiting. Both bodies are tidally locked (→ tidal locking). This phenomenon is a natural consequence of → tidal braking. Synchronous rotation is common throughout the → solar system. It is found among the satellites of → Mars (→ Phobos and → Deimos), → Jupiter (most of Jupiter satellites, including the → Galilean Moons) and → Saturn (e.g. → Iapetus). Similarly, → Pluto and its moon → Charon are locked in mutual synchronous rotation, with both of them keeping the same faces towards each other.

→ synchronous; → rotation.