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

An intervening substance through which an effect is produced; surrounding objects, conditions, or influences; environment. → interstellar medium.

From L. medium, from neut. of adj. medius "middle," from PIE *medhyo- "middle;" cf. Av. maδəma- "middle," as below.

Madim, from Av. maδəma- [adj.] "middle, being in the middle; middling, of a middling size or quality," maiδim "in the midst of," maiδyāna- "the middle;" cf. Skt. mádhya- "middle;" Gk. messos; Goth. midjis; O.E. midd "middle;" O.C.S. medzu "between," Arm. mej "middle;" L. medium, as above.

To come upon; come into the presence of; encounter.

M.E. meten, from O.E. metan "to find, find out; encounter; obtain," cognate with O.Frisian meta, O.Sax. motian "to meet," Goth. gamotijan, ultimately from PIE root *mod- "to meet, assemble."

Mavâzidan, from Sogd. mwz "to meet together, encounter" (Cheung 2007); ultimately from Proto-Ir. *ham-uaz-, from *ham- "together, → com-," + *uaz- "to move, carry, drive;" cf. Av. vaz- "to move, carry, drive (a chariot);" Pers. vazidan "to blow;" parvâz "→ flight."

1) The act of coming together.
2) An → assembly or conference of persons for a specific purpose (Dictionary.com).

→ meet; → -ing.

1) Prefix, often meaning "large, great."
2) Prefix meaning 10⁶.

From Gk. megas "great, large, mighty," from PIE *meg- "great;" cf. L. magnus, Goth. mikils, O.E. micel.

A unit of distance equal to a million → parsec (pc)s, or 3.26 million → light-years.

→ mega-; → parsec.

Same as → Dyson sphere.

→ mega-; → structure.

A unit of explosive force equal to one million metric tons of → T.N.T.. 1 megaton = 4.2 × 10²² → ergs = 4.2 × 10¹⁵ → joules.

→ mega-; → ton.

One of the seven stars of the → Big Dipper, which links Ursa Major's tail to the Bear's hindquarters. Megrez is the dimmest of the Big Dipper stars at magnitude +3.3. It is an A3 dwarf, about 20 times more luminous that the Sun, lying 81 light-years away.

From Ar. al-Maghriz(المغرز) "the root, base, bottom" (of the Bear's tail).

A → giant star of → apparent visible magnitude 3.54 in the → Orion constellation. λ Ori is of → spectral type O8 III, has a mass of about 28 → solar masses, a size of about 10 → solar radii, and an → effective temperature of around 35,000 K. Meissa is a → soft X-ray source with a → luminosity of 10³² erg s^-1 and peak emission in the energy range of 0.2-0.3 keV, which is probably generated by the → stellar wind. Meissa is a member of the → Orion OB1 association. It is in fact a → double star with a → companion at an angular separation of 4.41 arcseconds. This fainter component has a magnitude of 5.61, is a → main sequence star of → spectral type B0.5 V. There is an outlying component, Meissa C, which is an F-type main sequence F8 V star. This star in turn may have a very low mass companion that is probably a brown dwarf. λ Ori, excites a fairly symmetric → H II region, Sh2-264 surrounding it. Many observational studies have found dark clouds external to this H II region.

Arabic al-maysan (مَیسان) "bright."

(v.int.) To become liquefied by warmth or heat, as ice, snow, butter, or metal. (v.tr.) To reduce to a liquid state by warmth or heat; to fuse.

M.E. melten, O.E. meltan "become liquid;" cf. O.N. melta "to digest;" Gk. meldein "to melt," L. mollis "soft, mild."

Godâxtan, godâz- "to melt," from Mid.Pers. vitâxtan, vitâcitan "to melt," from Av. vi-taxti- "flowing away, melting," from vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + tak- "to run, to flow," taciāp- "flowing water," tacinti (3pl.pers.act.) "to flow," tacar- "course," tacan "current, streaming;" Mod.Pers. tâz-, tâxtan "to run; to hasten; to assault," tâzi "swift (greyhound)," tak "running, rush;" Mid.Pers. tâz-, tâxtan "to flow, to cause to walk," tc- "to flow, to walk," tag "running, attack," tâzig "swift, fast;" Khotanese ttajs- "to flow, to walk;" cf. Skt. tak- "to rush, to hurry," takti "runs;" O.Ir. tech- "to flow;" Lith. teketi "to walk, to flow;" O.C.S. tešti "to walk, to hurry;" Tokharian B cake "river;" PIE base *tek^w- "to run; to flow."

A severe accident in a nuclear reactor which is caused by a major failure in the reactor cooling circuit leading to the melting of the reactor core. Without coolant, the core would overheat so that the uranium fuel would melt. If the core continued to heat up, the steel walls of the core would also melt. If the molten core escaped from the containment housing of the reactor, large amounts of highly radioactive materials would be released into the atmosphere. The radioactive contamination of the air, water, and soil can have disastrous consequences for life.

→ melt; down, M.E. doun, from O.E. dune "downward," short for adune, ofdune, from a-, of "off, from" + dune "hill."

Forugodâxt, from foru- "down, downward; below; beneath," as in forurixtan, forunešastan, foruraftan (Mid.Pers. frôt "down, downward;" O.Pers. fravata "forward, downward;" cf. Skt. pravát- "a sloping path, the slope of a mountain") + godâxt past stem of godâxtan, godazidan → melt.

The temperature at which a solid changes to a liquid.

→ melting; → point.

A person or a thing that is part of a group body; e.g. a star which belongs to a cluster.

From M.E., from O.Fr. membre, from L. membrum "limb, member of the body, part."

Hamvand, literally "linked, joined together," from ham- "together, with; same, equally, even" (Mid.Pers. ham-, like L. com- and Gk. syn- with neither of which it is cognate. O.Pers./Av. ham-, Skt. sam-; also O.Pers./Av. hama- "one and the same," Skt. sama-, Gk. homos-; originally identical with PIE numeral *sam- "one," from *som-. The Av. ham- appears in various forms: han- (before gutturals, palatals, dentals) and also hem-, hen-) + vand "joined, tied," from bastan, vastan "to bind, shut" (O.Pers./Av. band- "to bind, fetter," banda- "band, tie" (cf. Skt. bandh- "to bind, tie, fasten;" PIE *bhendh- "to bind;" Ger. binden; E. bind).

The state of being a member.

From → member + -ship a native E. suffix of nouns denoting condition, character, office, skill, etc., from M.E., O.E. -scipe; akin to shape.

hamvandi, from hamvand, → member, + -i condition, character suffix.

One of several functions used in the → fuzzification and → defuzzification steps of a → fuzzy logic system to map the → nonfuzzy input values to → fuzzy linguistic terms and vice versa. A membership function is used to quantify a linguistic term.

→ membership; → function.

To commit to memory, learn by heart.

From memor-, → memory, + → -ize.

Barmidan, from barm, → memory; az bar kardan, literally "to do from memory," from az preposition, bar, contraction of barm, kardan "to do, make," → -ize.

1) The faculty of the mind to preserve and recall past sensations, thoughts, knowledge, etc.
2) In computers and recording instruments, any device into which information can be introduced and later extracted.

M.E. memorie, from L. memoria, from memor "mindful, remembering;" cf. Gk. mermera "care," merimna "anxious thought, sorrow," martyr "witness;" Pers. šomârdan "to count;" Mid.Pers. ôšmârtan, ôšmurtan "to reckon, calculate, enumerate, account for;" from Av. base (š)mar- "to have in mind, remember, recall," pati-šmar- "to recall; to long for," hišmar-; Skt. smar- "to remember, become aware," smarati "he remembers."

Barm "memory," variant bar (az bar kardan "to memorize"), bir, vir, from Mid.Pers. varm "memory," variants vir, vârom "mind, conscience;" from Av. vārəma, vārəm "according to one's wishes," from var- "to choose."

The amount of information which can be retained in a memory, usually expressed as the number of words which can be retained. For comparison of different memories this number is expressed in bits.

→ memory; → capacity.

See → periodic table.

→ periodic table.

A → lens with a crescent-shaped section; a → concavo-convex lens.

Mod.L. meniscus, from Gk. meniskos "lunar crescent," diminutive of mene, → moon.

Mâhak, diminutive of mâh, → moon.
Kuž-kâv "convexo-concave," → convex; → concave.