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

An instrument for the measurement of angles, used in surveying. It consists essentially of a telescope moving along a circular scale graduated in degrees.

The first occurrence of the word theodolite is found in the surveying textbook A geometric practice named Pantometria (1571) by Leonard Digges, which was published posthumously by his son, Thomas Digges. The etymology of the word is unknown. The first part of the New Latin theo-delitus might stem from the Gk. theaomai "to behold, view attentively, contemplate," but the second part is more puzzling and is often attributed to an un-scholarly variation of delos "evident, clear."

A person versed in theology, especially Christian theology (Dictionary.com)

→ theology.

The field of study and analysis that treats of → God and of God's attributes and relations to the universe; study of divine things or religious truth; divinity (Dictionary.com).

→ theism; → -logy.

A → proposition, → statement, or → formula in → mathematics or → logic deduced from → axioms, other propositions, → assumptions, → premises, or formulas. Theorems are statements which can be proved. For example, → Fourier theorem; → Liouville's theorem; → Woltjer's theorem.

From M.Fr. théorème, from L.L. theorema, from Gk. theorema "spectacle, speculation," in Euclid "proposition to be proved," from theorein "to look at, speculate, consider."

Farbin, from far- intensive prefix "much, abundant; elegantly; forward" (Mid.Pers. fra- "forward, before; much; around;" O.Pers. fra- "forward, forth;" Av. frā, fərā-, fra- "forward, forth; excessive;" cf. Skt. prá- "before; forward, in front;" Gk. pro "before, in front of;" L. pro "on behalf of, in place of, before, for;" PIE *pro-) + bin, present stem of didan "to see," from Mid.Pers. wyn-; O.Pers. vain- "to see;" Av. vaēn- "to see;" cf. Skt. veda "I know;" Gk. oida "I know," idein "to see;" L. videre "to see;" PIE base *weid- "to know, to see."

Of, pertaining to, or consisting in theory.

From L.L. theoreticus "of or pertaining to theory," from Gk. theoretikos "contemplative, pertaining to theory;" → theory.

Negarik, contraction of negaréik, from negaré→ theory + -ik, → -ic.

An astrophysical study or research group mainly concerned with theory rather than observation.

→ theoretical; → astrophysics.

One who formulates or is expert in the theoretical side of a subject.

From theoretic, from theoretics, from → theory + -ian.

Negare-pardâz, from negaré, → theory, + pardâz, present stem of pardâxtan "to accomplish; bring to perfection; to attempt, to care; to clean; to free;" Mid.Pers. pardâxtan, pardâzidan "to accomplish; to be done with, freed of" ultimately from Proto-Iranian *para-tāxta-, *para-tāca- "to take away; to expel," from *para- "along, forth," → para-, + tāxta-, tāca- "to run, to flow;" cf. Av. tak- "to run, to flow;" Mod.Pers. tâxtan, tâz- "to flow, to cause to walk," → flow.

Same as → theoretician.

From theor-, from → theory + -ist a suffix of nouns, often corresponding to verbs ending in -ize or nouns ending in -ism.

→ theoretician.

A coherent set of verified facts, propositions, or principles analyzed in their relation to one another and used to explain and predict phenomena, e.g. the → theory of relativity. The criterion of the scientific status of a theory is its → falsifiability, → refutability, or → testability. See also → hypothesis, → model.

From L.L. theoria, from Gk. theoria "contemplation, speculation, a looking at, things looked at," from theorein "to consider, view, look at," from theoros "spectator," from thea "a view" + horan "to see."

Negaré, from negar present stem of negaridan, negaristan "to look, observe;" Mid.Pers. nigeridan, niger-, nikiritan, nikir- "to look, to watch, to notice, to consider;" ultimately from Proto-Iranian *ni-kar-, from *ni- "down, in, into," → ni- (PIE), + *kar- "to observe, to consider;" cf. Av. kar- "to remember; to impress on memory;" Skt. kal- "to observe, consider," kalayati "considers, observes;" Mid.Pers. kartan "to establish; to declare; to found," (h)angârtan "to consider, to bear in mind, to regard as," us-kâritan "to consider, deliberate, discuss," sikâl, sigâl "thought;" Mod.Pers. engâridan, engâštan "to suppose," segâl "thought," segâlidan "to think, to resolve to injure, to deceive."

Any theory that attempts to describe all the forces of nature including gravity in a single mathematical formalism; e.g. → grand unified theory. → string theory.

→ theory; every; M.E. every, everich; O.E. æfre ælc "ever each;" → thing.

Negaré, → theory; hamé, → all; ciz, → thing.

Any of the two theories put forward by Albert Einstein: → special relativity (1905) and → general relativity (1916).

→ theory; → relativity;

Any of several commercial units of heat energy, as one equivalent to 10⁶ calories.

From Gk. therme "heat," → thermal.

Of, pertaining to, or caused by heat or temperature.

From M.Fr. thermal, from Gk. therme "heat," cognate with Pers. garm "warm," as below.

Garmâyi, adj. of garmâ "heat, warmth," from Mid.Pers. garmâg; O.Pers./Av. garəma- "hot, warm;" cf. Skt. gharmah "heat;" cognate with Gk. therme, thermos, as above; PIE *ghworm-/*ghwerm- "warm."

1) The random movement of the molecules of a substance, the energy of which is, by kinetic theory, synonymous with the heat content of the substance.
2) Solid state physics: The random motion of free electrons in a conductor due to heat energy.

→ thermal; → agitation.

The emission of electromagnetic radiation from high temperature plasma, produced as electrons are deviated by positive ions. Same as → free-free emission

→ thermal; → bremsstrahlung.

A process that occurs in a medium where a → temperature gradient exists: dQ = -κ(dT/dx)dA.dt, where dQ is the amount of heat passing through the time dt across an area dA in the direction of the normal x to this area and toward the reduction in temperature, κ is the → thermal conductivity, and (dT/dx) the temperature gradient.

→ thermal; → conduction.

In → thermal conduction, the amount of heat passing across unit area per unit time and per unit → temperature gradient.

→ thermal; → conductivity.

A detector that senses the change of temperature due to the absorption of photons.

→ thermal; → detector.

A physical process resulting from → temperature gradients in stellar interiors, whereby more highly charged and more massive chemical species are concentrated toward the hottest region of the star, its center. Therefore, thermal diffusion and → gravitational settling tend to make heavier species sink relative to the light ones.

→ thermal; → diffusion.

→ thermal radiation.

→ thermal; → emission.