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

A measure of a force's tendency to cause a body to → rotate about a specified → axis. It is given by the force times the perpendicular → distance of the → line of action from the axis. Same as → torque

→ moment; → force.

A quantity which is a measure of the inertness of a body in rotatory motion about an axis. It is equal to the sum of the products of the masses of all particles of the body by the squares of their distances from this axis: I = Σm_ir_i², where r_i is the distance of the particle of mass m_i from the axis. Moment of inertia depends only upon the shape of the body and the arrangement of its mass with respect to the axis. For a solid sphere it is (2/5)MR². Moment of inertia is used in place of mass in problems involving rotation. Thus, the → angular momentum is Iω and → angular kinetic energy is (1/2)Iω², where ω is → angular velocity.

→ moment; → inertia.

Same as → angular momentum.

→ moment; → momentum.

In → Newtonian mechanics, the momentum p of a body with → mass m and → velocity v is the product of these two quantities: p = mv. Momentum usually means → linear momentum as opposed to → angular momentum.

From L. momentum "movement, moving power," from movere "to move," → move.

Jonbâk, from jonb present stem of jonbidan "to move" (Mid.Pers. jumbidan, jumb- "to move," Lori, Laki jem "motion," related to gâm "step, pace;" O.Pers. gam- "to come; to go," Av. gam- "to come; to go," jamaiti "goes," gāman- "step, pac;" 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") + -âk noun suffix.

1) Philo.: The doctrine that reality consists of an unchanging whole in which change is mere illusion. → pluralism.
2) Philo.: The doctrine that the person consists of only a single substance, or that there is no crucial difference between mental and physical events or properties.
3) The attempt to explain anything in terms of one principle only. → dualism, → materalism, → idealism (Dictionary.com).

→ mono-; → -ism.

1) (v.) To watch closely or evaluate something on a constant or regular basis.
To oversee, supervise, or regulate.
2) (n.) A video device that displays data or images generated by a computer or terminal.

From L. monitor "one who reminds, admonishes, or checks," from monere "to remind, warn, advise," related to memini "I remember, I am mindful of," mens "mind," from PIE base *men- "to think;" Pers. cognates under → idea.

Pahregar "watch, guard," agent noun from pahré (Dehxodâ) "watch, guarding," from Mid.Pers. pahr, pahrag "guard;" Av. pāθra.vant "guard, watchman," from *pāθra-, from Av. pā- "to protect," pāti "guards," nipā(y)- (with → ni-) "to watch, observe, guard," nipātar- "protector, watcher," nipāθri- "protectress;" cf. Skt. pā- "to protect, keep," tanû.pā- "protecting the body," paś.pā- "shepherd;" Gk. poma "lid, cover," poimen "shepherd;" L. pascere "to put out to graze," pastor "shepherd;" Lith. piemuo "shepherd;" PIE base *pā- "to protect, feed."
Pahridan verb from pahr, as above.

1) A combining form meaning "alone, single, one," as in monochromatic, Monoceros, monotonic.
2) In chemistry applied to compounds containing one atom of a particular element (monohydrate).

From Gk. mono-, from monos "single, alone," from PIE base *men- "small, isolated," also represented by Gk. manos "rare, sparse."

Tak "single, alone", from Mid.Pers. tak "single, alone," maybe related to tâk, tâi "unit, piece."
Yek "one, alone," from Mid.Pers. êwak (Proto-Iranian *aiua-ka-); O.Pers. aiva- "one, alone;" Av. aēuua- "one, alone;" cf. Skt. éka- "one, alone, single; " Gk. oios "alone, lonely;" L. unus "one;" Ger. ein; E. one.
Yektâ-, from yek, as above, + tâ "fold, plait, ply; piece, part," also a multiplicative suffix; Mid.Pers. tâg "piece, part."
Mono-, loan from Gk., as above.

The Unicorn. An extensive but faint constellation across the celestial equator , at 7h right ascension, 4° south declination. Abbreviation: Mon; genitive: Monocerotis.

Monoceros "the unicorn," from O.Fr., from L., from Gk. monokeros, from → mono- "single" + keras "horn," kara "head," karena "head, top;" cf. Pers. soru "horn," sar "head;" L. cornu "horn," cerebrum "brain;" Skt. śiras- "head, chief;" O.E. horn "horn of an animal," also "wind instrument" (originally made from animal horns), from P.Gmc. *khurnaz (Ger. Horn, Du. horen), from PIE *ker- "head, horn, top, summit."

Takšâx, from tak "single" → mono- + šâx "horn, branch" (Mid.Pers šâk; cf. Skt. sakha- "a branch, a limb;" Arm. cax; Lith. šaka; O.S. soxa; PIE *kakhâ "branch").

A faint filamentary loop of nebulosity about 1 kpc distant, the remnant of a supernova that occurred about 300,000 years ago. It contains the Rosette Nebula as well as the Cone Nebula.

→ Monoceros; → loop.

Characterized by light of one color or by radiation of a single wavelength or narrow range of wavelengths.

→ mono-; → chromatic.

The sum of → absorption coefficient (κ_ν) and → scattering coefficient (σ_ν) at a given frequency: k_ν = κ_ν + σ_ν. See also the → Rosseland mean opacity.

→ monochromatic; → opacity.

1) A single algebraic term, such as 2xy, 125, 2x². The → degree of the monomial is the sum of the exponents of all included variables. Constants have the monomial degree of 0.
2) Of, pertaining to, or consisting of a monomial.

→ mono- + nomial, short for → nomnial.

A → morphismf : Y → X if, for any two morphisms u,v : Z → Y, f u = f v  implies that u =v.

→ mono-; → morphism.

The fact of having only a single meaning. Same as → univocity. Compare with → polysemy.

From → mono- "single," + sem, from sema "sign," → semantic, + -y.

Takcemi, from tak-, → mono-, + cem, → meaning, + noun suffix -i.

The belief or doctrine that there is only one → God.

→ mono-; → theism.

Of a mathematical function, either continuously increasing or decreasing.

From Fr. monotone, from Gk. monotonos "monotonous, of one tone," from monos, → mono- "single, alone" + tonos "tone" + → -ic.

Yeknavâxt "monotonous," from yek "one, single," + navâxt"rhythm," from navâxtan, navâzidan "to play an instrument; to gratify," navâ "music, song, melody;" Mid.Pers. nw'c "to treat kindly, honour," niwag "music, melody;" Proto-Iranian *ni-uac-, from *ni- (→ ni-) + *uac- "to speak, treat kindly," → word.

A seasonal change in wind direction bringing dry air or heavy rain in India and nearby lands.

Monsoon, from Du. monssoen, from Port. monçao, from Ar. mausim "season." It was first applied to the winds over the Arabian Sea, which blow for six months from northeast and for six months from southwest, but it has been extended to similar winds in other parts of the world.

Bâd, → "wind;" mowsem, related to mowsem, from Ar. mausim, as above.

A computer-intensive technique that relies on repeated random sampling of a statistical population to compute its results. Monte Carlo simulation is often used for approximate numerical computations when application of strict methods requires too much calculation, or when it is infeasible or impossible to compute an exact result with a deterministic algorithm.

The term Monte Carlo was coined in the 1940s by physicists (Stanislaw Ulam, Enrico Fermi, John von Neumann, and Nicholas Metropolis) working on nuclear weapon projects in the Los Alamos National Laboratory. The name is a reference to a famous casino in Monaco which, it is said that, Ulam's uncle would borrow money to gamble at. → method.

A period of time based on the revolution of the Moon around the Earth. Several types of months are defined: → anomalistic month; → draconic month; → sidereal month; → synodic month; → tropical month.

O.E. monað, from P.Gmc. *mænoth- (O.N. manaðr, M.Du. manet, Du. maand, O.H.G. manod, Ger. Monat, Goth. menoþs "month"), related to *mænon-, → moon.

Mâh and mâng in Pers. are variants of the same term, the dominant form being mâh, while mâng (Av. from, see below) is used in classical literature as well as in some dialects: Tabari, Kurd. mâng, Laki, Tâti, Taeši mong, Šahmirzâdi, Sangesari mung; Mid.Pers. mâh "moon, month;" O.Pers. māha- "moon, month;" Av. māh- "month, moon," also māwngh-; cf. Skt. mās- "moon, month;" Gk. mene "moon," men "month;" L. mensis "month;" O.C.S. meseci, Lith. menesis "moon, month;" O.Ir. mi, Welsh mis, Bret. miz "month;" O.E. mona; E. moon, month; Ger. Mond, Monat; Du. maan; PIE base *me(n)ses- "moon, month."

Note: In Persian the same term, mâh, is used for two different, but related, concepts: moon and month. This was also the case for other IE languages, as shows the above etymology. However, other IE languages have evolved toward more accuracy by using different forms of the same initial term, as in E. moon / month or Ger. Mond / Monat. The Latin family uses two unrelated words, as in Fr. lune "moon" / mois "month" and Sp. luna / mes. An additional difficulty in present Pers. is that the adj. mâhi not only means "lunar" and "monthly" it also denotes "fish." For the sake of clarity and precision, this dictionary uses mângi for "lunar."

1) Natural satellite of the Earth. Mass 7.35 x 10²⁵ g = 1/81 or 0.0123 Earth's. Mean radius 1740 km = ~ 1/4 the Earth's; this relatively small size ratio makes the Earth-Moon system unique in the → solar system. Mean density 3.34 g cm^-3. Mean distance from Earth 384,400 km. → Escape velocity 2.38 km s^-1. → Surface gravity 162.2 cm s^-2 = 0.165 Earth's. → Sidereal period 27d 7h 43m 11s. → Eccentricity 0.0549. → Inclination of → orbital plane to → ecliptic 5° 8' 43''. → Obliquity 6° 41'. → Synodic period 29d 12h 44m 2s.9. → Orbital velocity 1.02 km s^-1. The Moon's average visual → Albedo is 0.12, a factor of three smaller than that of Earth. The Moon's → center of mass is displaced about 2 km in the direction of Earth. The average temperature on the surface of the Moon during the day is 107 °C. During the night, the average temperature drops to -153 °C. Studies of lunar rock have shown that melting and separation must have begun at least 4.5 x 10⁹ years ago, so the → crust of the Moon was beginning to form a very short time after the → solar system itself. Thickness of crust ~ 60 km; of mantle ~ 1000 km. Temperature of core ~ 1500 K. It would have taken only 10⁷ years to slow the Moon's rotation into its present lock with its → orbital period. Because of this → synchronous rotation, the Moon revolves once on its axis each time it orbits the Earth, thus always presenting the same face, the nearside, toward Earth. The Moon may have formed during a collision between the early Earth and a Mars-sized rocky planet about 4.6 billion years ago; → Theia.
2) A large body orbiting a planet.

O.E. mona, from P.Gmc. *mænon- (cf. O.S., O.H.G. mano, O.Fris. mona, O.N. mani, Du. maan, Ger. Mond, Goth. mena "moon"), cognate with Pers. mâh, as below, from PIE *me(n)ses- "moon, month."

Mâh and mâng in Pers. are variants of the same term, the dominant form being mâh, while mâng (Av. from, see below) is used in classical literature as well as in some dialects: Tabari, Kurd. mâng, Laki, Tâti, Taelši mong, Šahmirzâdi, Sangesari mung; Mid.Pers. mâh "moon, month;" O.Pers. māha- "moon, month;" Av. māh- "month, moon," also māwngh-; cf. Skt. mās- "moon, month;" Gk. mene "moon," men "month;" L. mensis "month;" O.C.S. meseci, Lith. menesis "moon, month;" O.Ir. mi, Welsh mis, Bret. miz "month;" O.E. mona; E. moon, month; Ger. Mond, Monat; Du. maan; PIE base *me(n)ses- "moon, month."

Note: In Persian the same term, mâh, is used for two different, but related, concepts: moon and month. This was also the case for other IE languages, as shows the above etymology. However, other IE languages have evolved toward more accuracy by using different forms of the same initial term, as in E. moon / month or Ger. Mond / Monat. The Latin family uses two unrelated words, as in Fr. lune "moon" / mois "month" and Sp. luna / mes. An additional difficulty in present Pers. is that the adj. mâhi not only means "lunar" and "monthly" it also denotes "fish." For the sake of clarity and precision, this dictionary uses mângi for "lunar."