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

1) The act or process of reionizing a gas; an instance of this action.
2) The → ionization of → neutral hydrogen atoms formed during → recombination epoch in the → early Universe. See also → reionization epoch.

→ re-; → ionize.

An early epoch in the → Universe's history, but after the → recombination epoch, when the → first stars formed and their → ultraviolet light began to ionize the → neutral hydrogen gas that filled the Universe. The epoch of reionization is estimated to last between → redshifts of 12 to 6 (or when the Universe had between 2 and 5% of its age). Reionization marks the end of the → Dark Age in cosmic history.

→ reionization; → epoch.

1) To become → ionized again.
2) To → ionize again.

→ re-; → ionize.

A type of electrically charged → black hole that is spherically symmetric and non-rotating. Another type of such objects is the → Kerr-Newman black hole.

Named after the German physicist Hans Jacob Reissner (1874-1967) in 1916 and the Finnish Gunnar Nordstrom (1881-1923) in 1918 independently worked out solutions different from those of Schwarzschild; → black hole.

To refuse to accept, take, consider, recognize, etc.

→ re- + jec-, combining form of jacere "to throw" + -tus p.p. suffix, → project.

1) (tr.) To find or show a connection between two or more people or things.
2) (intr.) To have a significant connection with or bearing on something.

From O.Fr. relater, from L. relatus literally "carried, brought back," from re- "back, again" + latus "carried, brought," used as p.p. of referre, from re- "back, again" + ferre "carry, bear," cognate with Pers. bordan "to carry, bear" (Mid.Pers. burdan, O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive)," Skt. bharati "he carries," Gk. pherein, L. fero "to carry;" PIE base *bher- "to carry").

Bâzânidan, literally "to bring, lead back," from bâz- "back, again," → re- + ân stem of ânidan "to bring; to lead; to guide," cf. dialectical Kurd. ânin "to bring, to lead to," Tâleši ânân, ânoe "to bring together two edges;" Mid.Pers. ônidan, nidan, nay- "to lead; to bring;" O.Pers. nay- "to lead; to bring" anaya "leads;" Av. nay- "to lead; to bring," naiieiti "leads;" cf. Skt. nī- "to lead," náyati "leads," aorist s. anait.

Connected; associated.

P.p. of → relate.

General: A connection or association between two or more things.
Math.: A property that associates two quantities in a definite order, as equality or inequality.

Verbal noun of → relate.

Same as → predicate symbol.

→ relation; → symbol.

Of or pertaining to relations.

→ relation + → -al.

A type of data structure in which data are represented as tables in which no entry contains more than one value.

→ relational; → data; → structure.

A database management system in which a relational data structure is used.

→ relational; → system.

(adj.): Existing or having its specific nature only by relation to something else; not absolute or independent.
See also: → relative atomic mass, → relative azimuth, → relative dating, → relative density, → relative error, → relative frequency, → relative humidity, → relative invariant, → relative tensor, → relative vector, → relative permeability, → relative refractive index, → relative sunspot number, → relative velocity, → relatively, → relativity.

From M.E. relatif (n.), from O.Fr. relatif, from L.L. relativus "having reference or relation," from L. relatus, suppletive p.p. of referre "to refer," → relate.

Bâzâni, from bâzân- present stem of bâzânidan, → relate, + -i adj. suffix.

The ratio of the mass of an atom of the → chemical element to one-twelfth the mass of an atom of carbon-12. Because an element in nature is usually a mixture of isotopes, the relative atomic mass is also the weighted mean of the atomic masses of all the atoms in a particular sample of the element, weighted by isotopic abundance. In this sense, relative atomic mass was once known as → atomic weight.

→ relative; → atomic; → mass.

The difference in → azimuth between the → Moon and the → Sun.

→ relative; → azimuth.

A method of dating that can only tell us whether an event or object is older or younger than another event or object. In geology, different layers of rock are compared to determine an ordered sequence of events in geologic history. In contrast to → absolute dating, relative dating cannot give the actual age of a rock. See also → stratigraphy.

→ relative; → dating.

The ratio of the density of a substance to the density of a given reference material. For a solid or liquid, it is the density (at 20°C) relative to the maximum density of water (at 4°C). For a gas is its density divided by the density of hydrogen (or sometimes dry air) at the same temperature and pressure. Also called → specific density.

→ relative; → density.

The → absolute error divided by the true value x, that is: Δx/x. The result may be expressed as a percentile and is useful when we want to determine the error relative to the value of the exact quantity.

→ relative; → error.

Statistics: The number of the occurrences of an event divided by the number of observations.

→ relative; → frequency.

The amount of moisture in the air compared to what the air can "hold" at that temperature. It is given by the ratio of the partial pressure of water vapor in the mixture to the saturated vapor pressure of water at a specific temperature.

→ relative; → humidity.