An Etymological Dictionary of Astronomy and Astrophysics

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory



<< < -me mac mag mag mag mag mai Mal mar mas mas mat Max mea mec mel mer mes met met met mic mid mil min mis mne mod mol mon Mor mou mul muo > >>

Number of Results: 679
meteorological observatory
  نپاهشگاه ِ هواشناختی   
nepâhešgâh-e havâšenâxti

Fr.: observatoire météorologique   

A scientific establishment dedicated to making precise and detailed meteorological observations and to studying and forecasting atmospheric phenomena by means of special equipments.

Meteorological, of or pertaining to → meteorology; → observatory.

havâšenâsi (#)

Fr.: météorologie   

The study of the physics, chemistry, and dynamics of the Earth's atmosphere, including the related effects at the air-earth boundary over both land and the oceans.

From Gk. meteorologia "discussion of celestial phenomena," from meteoronmeteor + -logia, &rarr-logy.

Havâšenâsi, from havâ "weather, air," → air.

metr (#)

Fr.: mètre   

The fundamental unit of length in the metric system, now defined as 1/299,792,458 of the distance light travels in a vacuum in one second. Abbreviation: m.

From Fr. mètre, from Gk. metron "measure," from PIE base *me- "to measure" (cf. O.Pers., Av. mā- "to measure;" Skt. mati "measures;" L. metri "to measure").

Metr, loan from Fr.

metân (#)

Fr.: méthane   

A colorless, odorless, inflammable gas gas of formula CH4; the simplest hydrocarbon.

From meth- a combining form representing methyl + -ane a suffix used in names of hydrocarbons of the methane or paraffin series.

metânol (#)

Fr.: méthanol, alcool méthylique   

Alcohol, also known as methyl alcohol, formula CH3OH, formed in small quantities in the oxidation of methane. → methanol maser.

From → methane + -ol a suffix used in the names of chemical derivatives.

methanol maser
  میزر ِ متانول   
meyzer-e metânol

Fr.: maser méthanol   

A maser source in which excited methanol molecules (CH3OH) produce → maser emission. Methanol masers are signposts of the early stages of star formation, many being associated with sources that have not developed an → H II region. There are more than 20 different methanol transitions that have been observed. They are divided into two categories: Class I, excited by collisions, and class II, excited by infrared radiation. The most important class I masers are at a frequency of 44.1 GHz, while he most important class II masers are at a frequency of 6.7 GHz.

methanol; → maser.

raveš (#)

Fr.: méthode   

A manner or mode of procedure, especially an orderly, logical, or systematic way of instruction, inquiry, investigation, experiment, and so on.

From M.Fr. méthode, from L. methodus "way of teaching or going," from Gk. methodus "scientific inquiry, method of inquiry," originally "following after," from → meta- "after" + hodos "way."

Raveš "mthod," originally "going, walking," from row "going," present stem of raftan "to go, walk;" Mid.Pers. raftan, raw-, Proto-Iranian *rab/f- "to go; to attack" + -eš a suffix of verbal nouns.

method of least squares
  روش ِ کمترین چاروش‌ها   
raveš-e kamtarin cârušhâ

Fr.: méthode des moindres carrés   

A method of fitting a curve to data points so as to minimize the sum of the squares of the distances of the points from the curve.

method; → least squares.

method of small perturbations
  روش ِ پرتورش‌های ِ کوچک   
raveš-e parturešhâ-ye kucak

Fr.: méthode des petites perturbations   

The linearization of the appropriate equations governing a system by the assumption of a steady state, with departures from that steady state limited to small perturbations. Also called perturbation method.

method; → small; → perturbation.

method of successive approximations
  روش ِ نزدینش‌های ِ پیاپی   
raveš-e nazdinešhâ-ye payâpey

Fr.: méthode d'approximations successives   

The solution of an equation or by proceeding from an initial approximation to a series of repeated trial solutions, each depending upon the immediately preceding approximation, in such a manner that the discrepancy between the newest estimated solution and the true solution is systematically reduced.

method; → successive; → approximation.


Fr.: méthyle   

A → methane molecule lacking one → hydrogen atom: CH3. → methyl chloride.

Back formation from Fr. méthylène, → methylene.

methyl chloride
  کلرور ِ متیل   
klorur-e metil

Fr.: chlorure de méthyle   

A → chemical compound (CH3Cl), which is the most abundant → organohalogen in the Earth's atmosphere. It has both natural and synthetic origins. Also called chloromethane. Low levels of methyl chloride occur naturally in the environment. Methyl chloride is formed in the oceans by natural processes (e.g., marine phytoplankton) and from biomass burning in grasslands and forested areas (e.g., forest fires); it has been detected at low levels in air all over the world. Other sources of exposure to methyl chloride include cigarette smoke, polystyrene insulation, and aerosol propellants; home burning of wood, coal, or certain plastics. High levels may occur at chemical plants where it is made or used. Acute (short-term) exposure to high concentrations of methyl chloride in humans has caused severe neurological effects. Methyl chloride has also caused effects on the heart rate, blood pressure, liver, and kidneys in humans (United States Environmental Agency, EPA).

methyl; → chloride.


Fr.: Métis   

The innermost moon of → Jupiter. Also known as Jupiter XVI. It was discovered in 1979 in images taken by Voyager 1. Its mass is about 3.6 × 1016 kg and its dimensions 60 × 40 × 34 km. Its mean distance from Jupiter is 128 000 km and its → orbital period is 0.29 Earth days, which is faster than Jupiter's rotation period. Metis is one of the → Shepherd moons of Jupiter.

Named in 1983 after the first wife of Zeus.

Metonic cycle
  چرخه‌ی ِ متون   
carxe-ye Meton

Fr.: cycle de Méton   

A time interval lasting 235 → lunations, or about 19 → tropical years (235 = 19 x 12 + 7), after which → lunar phases recur on the same days of the year.

Named after Meton of Athens, a Gk. mathematician, astronomer, geometer, and engineer who used it in 432 B.C., but it was known to the Babylonians by around 500 B.C. and to the Chinese around 600 B.C.; → cycle.

  ۱، ۲) متریک؛ ۳) متری   
1), 2) metrik (#); 3) metri (#)

Fr.: métrique   

1) A mathematical → expression consisting of an → array of → components which are needed for calculating → infinitesimally small → distances between two → points in some geometrical → space. More simply put, the → function used to define a distance between two points in a → metric space. Also called → distance function.
2) In → general relativity the metric describes the → space-time geometry and gives the interval between two neighboring → events.
3) Pertaining to the meter or to the → metric system.

From → meter + → -ic.

metric prefix
  پیشوند ِ متری   
pišvand-e metri

Fr.: préfixe du système international d'unités   

Any of the suffixes adopted by the International System of Units (→ SI units).
For numbers larger than 1: → deca- (101), → hecto- (102), → kilo- (103), → mega- (106), → giga- (109), → tera- (1012), → peta- (1015), → exa- (1018), → zetta- (1021), and → yotta- (1024) .
For numbers smaller than 1: → deci- (10-1), → centi- (10-2), → milli- (10-3), → micro- (10-6), → nano- (10-9), → pico- (10-12), → femto- (10-15), → atto- (10-18), → zepto- (10-21), and → yocto- (10-24).

metric; → prefix.

metric space
  فضای ِ متریک   
fazâ-ye metrik

Fr.: espace métrique   

An set of points such that the distance between every pair of points is defined by a → distance function with the following properties: 1) the distance from the first point to the second equals zero if and only if the points are the same, 2) the distance from the first point to the second equals the distance from the second to the first, and 3) the sum of the distance from the first point to the second and the distance from the second point to a third exceeds or equals the distance from the first to the third.
In mathematical language, the properties, for a nonempty set X, can be expressed as:
1) d(x,y)≥ 0 and d(x,y) = 0 if and only if x = y.
2) d(x, y) = d(y,x) for all x, y ∈ X.
3) d(x,z)d(x,y) + d(y,z) for all x, y, and z ∈ X. Also called → triangle inequality.

metric; → space.

metric system
  راژمان ِ متری   
râšmân-e metri

Fr.: système métrique   

A standard system of measurement using decimal units, in which the units of length, time, and mass are meter, second, and kilogram respectively.

metric; → system.

metric tensor
  تانسور ِ متریک   
tânsor-e metrik

Fr.: tenseur métrique   

The abstract tensor operation which is computed in a particular → reference frame using the → metric components. The metric tensor defines magnitude and direction of vectors about a point.

metric; → tensor.

metric unit
  یکای ِ متری   
yekâ-ye metri (#)

Fr.: unité métrique   

A physical → measurement unit in the → metric system.

metric; → unit.

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