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

1) To deny the existence or truth of.
2) To cause to be ineffective or invalid.

From L. negatus p.p. of negare "to say 'no', deny," from Old L. nec "not," from PIE base *ne- "no, not."

Nâyidan infinitive from nâ "no, not," variants na, ni, ma- (prohitive); from Mid.Pers. nê, ma "no, not;" O.Pers. naiy, nai "not;" Av. nôit, naē "not;" cf. Skt. ná "not;" cf. L. ne-, in-, un-; Gk. ni; Lith. nè; O.C.S. ne "not;" PIE *ne-, as above.

1) The act of denying; → denial.
2) The absence or → opposite of something that is actual, positive, or affirmative.
3) A → negative statement, idea, doctrine; a contradiction, refutation, or rebuttal.
4) Logic: If p is a → proposition, then the statement "not p," denoted ¬ p, is the negation or opposite of p. If p is "It is sunny," then ¬ p is "It is not sunny." If p is → true, then ¬ p is → false, and vice versa.

Verbal noun of → negate.

1) General: Expressing, containing, or consisting of a negation, refusal, or denial.
2) Math.: Of or relating to a quantity less than zero. Of or relating to the sign (-).
3) Physics: Of or relating to an electric charge of the same sign as that of an electron.
4) Photography: Having dark for light and light for dark.
5) Opposite of → positive.
See also:
→ negative charge, → negative correlation, → negative crystal, → negative feedback, → negative lens, → negative number, → negative polarization, → negative pressure, → negative skewness.

From O.Fr. negatif (fem. negative), from L. negativus, "denying, inhibiting (legal actions); denied/refused; negative," from negare "to refuse, say 'no'" from Old L. nec "not", from Italic base *nek- "not," from PIE base *ne- "no, not."

Nâyidâr, from nâyidan, → negate, on the model of xaridâr, foruxtâr, xâstâr, virâstâr, etc.

An electric charge that has the same sign as the electron.

→ negative; → charge.

A correlation between two variables such that as one variable's values tend to increase, the other variable's values tend to decrease.

→ negative; → correlation.

A uniaxial, birefringent crystal in which the velocity of the extraordinary ray surpasses that of the ordinary ray.

→ negative; → crystal.

A → feedback process in which the → output reacts on the → input so as to reduce the initial → effect.

→ negative; → feedback.

Same as → divergent lens.

→ negative; → lens.

A → real number that is less than zero. A negative number is indicated by the → minus sign.

→ negative; → number.

A type of polarization in which the direction of polarization becomes reversed.

→ negative; → polarization.

A kind of pressure that contrarily to ordinary pressure pushes inward. In contrast with the → Newtonian mechanics, in → general relativity there are situations in which pressure can be negative. Positive pressure gives rise to attractive gravity, whereas negative pressure creates → repulsive gravity.

→ negative; → pressure.

Of a distribution function, a skewness in which the left tail (tail at small end of the distribution) is more pronounced that the right tail (tail at the large end of the distribution). → positive skewness.

→ negative; → skewness.

An obsolete term denoting a negatively charged electron, as opposed to a positron.

From → negative + → electron.

1) The area or region around or near some place or thing; vicinity. → solar neighborhood.
2) Math.: An → open set that contains a given point.

From neighbor, M.E., O.E. neahgebur, from neah→ near + -hood suffix denoting "state or condition of being;" M.E. -hode, -hod; O.E. -had "condition, position," cognate with Ger. -heit, Du. -heid.

Hamsâyegi, noun from hamsâyé "neighbor," literally "under, sharing the same shade," from ham-, → syn-, + sâyé, → shadow.

A period of → geologic time within the Cenozoic era, between 23 and 2.6 million years ago, which comprises the Miocene and Pliocene epochs.

From L. neo-, → new, + -gene, → gene.

A colorless, odorless, and tasteless gaseous chemical element; symbol Ne. Atomic number 10, atomic weight 20.179; melting point -248.67°C; boiling point -246.048°C. It was discovered from its bright red spectral lines by the Scottish chemist William Ramsay and the English chemist Morris William Travers in 1898 from a liquefied air sample. Neon is produced by carbon burning in massive stars and released into the Galaxy when they explode.

From Gk. neon neuter of neos, → new, so called because it was a newly discovered element.

A → nuclear fusion process that takes place in → massive stars and leads to the → production of → oxygen and → magnesium. It requires high temperatures and densities (around 1.2 × 10⁹ K and 4 × 10⁹ kg/m³).

→ neon; → burning.

The branch of meteorology that deals with clouds.

From Gk. nephos "cloud," nephele "cloud;" cognate with Pers. nam "moisture;" Av. napta- "moist," nabās-cā- "cloud," nabah- "sky;" L. nebula "mist," nimbus "rainstorm, rain cloud;" Skt. nábhas- "moisture, cloud, mist;" O.H.G. nebul; Ger. Nebel "fog;" O.E. nifol "dark;" PIE base *nebh- "cloud, vapor, fog, moist, sky" + → -logy.

Abršenâsi, from abr "cloud," from Mid.Pers. awr, abr (Laki owr, Baluchi haur, Kurd. Soriani hewr); Av. awra- "rain cloud, rain;" cf. Skt. abhra-"thunder cloud;" Gk. afros "scum, foam;" L. imber "rain;" also Sk. ambha- "water;" Gk. ombros "rain," PIE *mbhros "rain cloud, rain," from *mbh- + -šenâsi→ -logy.

The eighth planet from the Sun and the fourth largest by size in the → solar system. The equatorial radius of Neptune is 24,764 km (3.883 Earths), its → semi-major axis is 30.11 → astronomical units (4.50 × 10⁹ km), and its → orbital period is 164.8 yr. Neptune has at least 14 moons, the largest ones are → Triton, → Proteus, and → Nereid, whereas its smaller moons are: Naiad, Thalassa, Despina, Galatea, Larissa, Halimede, Sao, Laomedeia, Psamathe, and Neso. Neptune has an incredibly thick atmosphere comprised of 74% → hydrogen, 25% → helium, and approximately 1% → methane. Particles of icy methane in its upper atmosphere give Neptune its deep blue color. Large storms whirl through Neptune's upper atmosphere, and high-speed winds track around the planet at up 600 m/s, fastest recorded in the solar system. One of the largest storms ever seen was recorded in 1989. Called the → Great Dark Spot, it lasted about five years. Neptune has a very thin collection of → rings. They are likely made up of ice particles mixed with → dust grains and possibly coated with a carbon-based substance.

Named for the Roman god of the sea Neptune, Gk. Poseidon.

A ductile, silvery radioactive metal, a member of the actinide series; symbol Np. Atomic number 93; atomic weight 237.0482; melting point about 640°C; boiling point 3,902°C (estimated). It was discovered in 1940 by Edwin M. McMillan and Philip H. Abelson, who produced neptunium-239 (half-life 2.3 days) by bombarding uranium with neutrons from a cyclotron at the University of California at Berkeley.

The name derives from the planet → Neptune, since it is the next outer-most planet beyond the planet Uranus in the solar system and this element is the next one beyond uranium in the periodic table.