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

The branch of mathematics that studies the relationship between integers and their generalization.

→ number; → theory.

1) A symbol, group of symbols, or word used to express a number. For any number there is an infinite number of numeral expressions. For example, the number two can be written as 2, II, binary 10, 4/2, 18/8, etc.
2) Of, pertaining to, or consisting of numbers or numerals.

From L.L. numeralis "of, or belonging to number," → number + → -al

Šomârâl, from šomâr, → number, + -al, → -al.

A set of → symbols and → rules for representing → numbers. Same as → number system. See also: → Greek numeral system, → Roman numeral system, → Indian numeral system.

→ numeral; → system.

The quantity x in a fraction x/y). The quantity y is the → denominator.

L.L. numerator "a counter, numberer," from L. numera(re) "to number," → number + -tor a suffix forming personal agent nouns from verbs and, less commonly, from nouns.

Šomârân, agent noun of šomârdan, → number.

Relating to or expressed in numbers.

Adj. of → number.

The study of methods for approximation of solutions of various classes of mathematical problems including error analysis.

→ numerical; → analysis.

The prediction of the evolution of a system via numerical construction of approximate solutions to the governing equations.

→ numerical; → modeling.

Another name for → numerical modeling.

→ numerical; → simulation.

The second brightest star in the constellation → Sagittarius. It is a blue-white → massive star of → spectral type B2.5 V lying 225 → light-years away.

Unusual name of Babylonian origin, of unknown significance.

To undergo or show nutation.

Nutate, back formation from → nutation.

Kaltâvidan, verbal form of → kaltâv→ nutation.

Mechanics: A wobbling motion of a spinning rigid body, such as a top, as it precesses about its vertical axis.
Astro.: A slight nodding motion of the Earth's axis of rotation, which has a principal period of 18.6 years. It is primarily caused by lunar perturbations, and is superimposed on the precession of the equinoxes and moves the equinox as much as 17'' ahead of or behind its mean position.

Fromm L. nutation-, from nutat(us), p.p. of nutare "to wobble, to sway, to nod repeatedly," from nu "nod" + -ta frequentative suffix + -tus p.p. ending + -ion a suffix denoting action or condition.

Kaltâv, from Kermâni keletow, Malâyeri kallatow "wobbling," from kal, kalleh "head" + tâv, tow, tâb "swing, twist," from tâbidan "to twist, to spin."

Same as → equation of the equinoxes.

→ nutation; → right ascension.

A drive mechanism used to move a radar beam in a circular, spiral, or conical path periodically.

Agent noun of → nutate.

1) Nourishing; providing nourishment or nutriment.
2) Containing or conveying nutriment, as solutions or vessels of the body.
3) A nutrient substance (Dictionary.com).

From L. nutrientem, pr.p. of nutrire, → nourish.

Fârmand, from present stem of fâridan, + -mand.

1) Any substance or matter that, taken into a living organism, serves to sustain it in its existence, promoting growth, replacing loss, and providing energy.
2) Anything that nourishes; nourishment; food (Dictionary.com).

From L. nutrimentum "nourishment; support," from nutrire, → nourish.

Fârâk, from present stem of fâridan, → nourish, + -âk (as in xorâk, pušâk, etc.).

1) The act or process of nourishing or of being nourished.
2) The science or study of, or a course of study in, nutrition, especially of humans (Dictionary.com).

Verbal noun from L. nutrire, → nourish.

A person who is trained or expert in the science of nutrition.

→ nutrition; → -ist.

1) Serving to nourish; providing nutriment; nutritious.
2) Of, pertaining to, or concerned with nutrition (Dictionary.com).

Adjective and agent noun from L. nutrire, → nourish.

Same as → night blindness; opposite of → hemeralopia.

L.L. nyctalopia, from Gk. nukt, → night + al(aos) "blind" + -opia, akin to ope "view, look," ops "eye."

Šabkuri, from šab, → night, + kuri "blindness," from kur, → blind.

The mean square noise voltage across a resistance in thermal equilibrium is four times the product of the resistance, Boltzmann's constant, the absolute temperature, and the frequency range within which the voltage is measured. → Johnson-Nyquist noise.

Named after Harry Nyquist (1889-1976), a Swedish-born American physicist, who made important contributions to information theory. → Johnson-Nyquist noise; → formula.