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

1a) Math.: An unproved → assumption taken as basic in a mathematical system, and from which (in combination with other → postulates) the propositions of the system are derived, or in terms of which the propositions are proved. In modern usage, postulate is synonymous with → axiom.
1b) Physics: A fundamental principle. For example, the two postulates of special relativity of Einstein are: 1) The laws of physical phenomena are the same when studied in terms of two → reference frames moving at a constant velocity relative to each other. 2) The → velocity of light in free space is the same for all observers and is independent of the relative velocity of the source of light and the observer. See also → Planck postulate.
2a) General: To ask, demand, or claim. To claim or assume the existence or truth of, especially as a basis for reasoning or arguing.
2b) Math.: To assume as a postulate.

From L. postulatum "petition, thing requested," noun use of neuter of p.p. of postulare "to ask, request, demand," akin to poscere "to request."

Farâvas (on the model of piš-nahâd "proposition," and farâ-nemudan "to exhibit, expose"), from farâ-, → pro-, + vas. The second component from Av. vas- "to will, desire, wish, long for," vasəmi "I wish," vasna- "will, favor," ušti- "desire, wish, will," vasô, vasə "at one's will;" cf. O.Pers. vasiy "at will, greatly, utterly," vašna- "will, favor;" Mid.Pers. vasnâd "because, on account of." This word is extant in several Modern Iranian dialects: Tabari vessen "to wish, desire," Gilaki vâssan "to wish, desire," vâsti "desire; for, because, on account of;" Kurd. wistin "to desire, wish," Lâri avessa "to desire;" Nâyini vas "to like;" colloquial Tehrâni vâsé "for;" Lori, Malâyeri biza "pregnancy craving;" cognate with Skt. vaś- "to wish, want, desire," váśa- "wish, desire," vasēna "for, because;" Gk. ekon "voluntary;" PIE base *uek- "to wish."

A silvery-white metallic chemical element; symbol K (from L. kalium "potash"). Atomic number 19; atomic weight 39.0983; melting point 63.25°C; boiling point 760°C.

Coined by the English chemist Sir Humphrey Davy (1778-1829), who first isolated it in 1807 from electrolysis of caustic potash (KOH); from Mod.L. potassa, Latinized form of E. potash + -ium.

1) A latent ability that may or may not be developed; possibility.
2) Physics: The → work required to → move a unit positive → charge, unit magnetic pole, or an amount of → mass respectively from → infinity (i.e. a place infinitely distant from the causes of the field) to a designated point. Gravitational potential is always negative, but the electric or magnetic potentials may be positive or negative.
3) (adj.) Capable of being or becoming, as opposed to → actual.
See also:
→ chemical potential, → electric scalar potential, → electromagnetic potential, → equipotential surface, → excitation potential, → gravitational potential energy, → ionization potential, → kinetic potential, → magnetic vector potential, → potential barrier, → potential density, → potential difference, → potential energy, → potential energy curve, → potential field, → potential gradient, → potential well, → potentiality, → retarded potential, → scalar potential, → thermodynamic potential, → Yukawa potential.

From L.L. potentialis "potential," from L. potentia "power," potis "powerful, able, capable;" cognate with Av. paiti- "lord, husband;" Mod.Pers. -bad (sepah-bad "general, commander of an army"); Skt. páti- "master, husband;" Gk. posis "husband;" Lith. patis "husband."

Tavand, from tav- + -vand. The first component tav- is the stem of tavân "power, strength," tavânestan "to be powerful, able;" variants tâv, tâb, (dialects) tew "power;" Mid.Pers. tuwan "power, might;" O.Pers. tav- "to have power, to be strong, to be able," tauman- "power, strength," tunuvant- "powerful;" Av. tauu- (tu-) "to be able, strong," tavah- "power," təviši- "strength" (Mod.Pers. tuš "power, ability"); Skt. tavⁱ- "to be strong, to have authority," tavas-, tavisa- "strong, energetic," tavisi- "power, strength;" Gk. taus, saos "healthy;" L. tumere "to be swollen;" PIE *teu- "to swell, be strong." The second component -vand a suffix of adjectives and agent nouns, → actual.
Note: Tavand used as both noun and adjective, such as honarmand (n.) and mard-e honarmand (adj.).

Region in a field of force in which the potential is such that a particle, which is subject to the field, encounters opposition to its passage.

→ potential; → barrier.

Of a fluid parcel at pressure P, the density that it would acquire if adiabatically brought to a reference pressure.

→ potential; → density.

Between two points, the work done in taking the unit test object from one point to the other. Potential is a scalar quantity.

→ potential; → difference.

Of a system, the work done in changing the system from some standard configuration to its present state. Thus, if a body of mass m is raised vertically through a height h, the work done, mgh, is the increase in potential energy.

→ potential; → energy.

A plot that displays the → potential energy of a moving body as a function of its position. It is explained by the → conservation of energy and the conversion of potential energy into → kinetic energy and vice versa.

→ potential; → energy; → curve.

A field that has a → potential. A continuous → vector fieldA in a domain D is a potential field in D if and only if its → work around every closed curve C contained in D is zero: ∫A.ds = 0. Examples include the → gravitational field and the → electrostatic field.

→ potential; → field.

At a point, the rate of change of potential V, with distance x, measured in the direction in which the variation is a maximum. The intensity F of the field is proportional to the potential gradient, but is oppositely directed: F = -dV/dx.

→ potential; → gradient.

Region in a → field of force in which the potential decreases abruptly, and in the surrounding region of which the potential is larger.

→ potential; → well.

1) The state or quality of being potential. Something potential.
2) According to Aristotle, what has the possibility of having → form, in contrast to → actuality; the power to effect change.

→ potential + → -ity.

With a possibility of becoming actual; possibly.

→ potential; → -ly.

An asteroid that could make a threatening close approach to the Earth. In technical terms a PHA is defined as having an → absolute magnitude of 22 or brighter and an → Earth Minimum Orbit Intersection Distance (MOID) of less than 0.05 → astronomical unit or 7.5 million km.

→ potentially; → hazardous; → asteroid.

An instrument for measuring electrical quantities by balancing an unknown potential difference against a known potential difference.

From potenti(al), → potential + -o + → -meter.

1) Physics: The → rate of doing → work on transferring → energy, as expressed in ergs/sec, watts, etc. Same as → mechanical power.
2) Math.: An → exponent to which a given quantity is raised. The expression xⁿ is therefore known as "x to the n-th power."

M.E. pouer(e), poer(e), from O.Fr. povoir, noun use of the infinitive in O.Fr., "to be able," from V.L. *potere, from L. potis "powerful, able, capable;" cognate with Av. paiti- "lord, husband;" Mod.Pers. -bad (sepah-bad "general, commander of an army"); Skt. pái- "master, husband;" Gk. posis "husband;" Lith. patis "husband."

Tavân "power, strength," tavânestan "to be powerful, able;" Mid.Pers. tuwan "power, might," from O.Pers./Av. base tav- "to have power, to be strong, to be able," Av. tavah- "power," təviši- "strength," Mod.Pers. tuš, tâb "power, ability," O.Pers. tauman- "power, strength," tunuvant- "powerful," Skt. tu- "to be strong, to have authority," tavas-, tavisa- "strong, energetic," tavisi- "power, strength."

A function of the form f(x) = xⁿ, where n is a → real number.

→ power; → function.

A mathematical relationship between two quantities expressed by a → power function.

→ power; → law.

A series in which the terms contain regularly increasing powers of a variable. In general, a₀ + a₁x + a₂x² + ... + a_nxⁿ, where a₀, a₁, etc. are constants.

→ power; → series.

Same as → spectral density.

→ power; → spectral; → density.