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

Any of the four main → proposition forms treated in Aristotle's → syllogism:
The A form (universal affirmative): All P's are Q's,
The E form (universal negative): No P's are Q's,
The I form (particular affirmative): Some P's are Q's, and
The O form (particular negative) Some P's are not Q's.

Greek philosopher Aristotle (384-322 BC); → form.

A branch of mathematics that deals usually with integers, rational numbers, real numbers, or complex numbers under addition, subtraction, multiplication, and division. See also → compute, → computation, → count, → calculate, → calculus, → mathematics, → statistics.

O.Fr. arsmetique, from M.L. arithmetica, from Gk. arithmetike (tekhne) "(art, skill) of numbers," from arithmos "number."

Hesâb, from Ar. hisab.

Of n numbers a₁, a₂, ..., a_n, the quantity defined as: (a₁ + a₂ + ... + a_n)/n.

→ arithmetic; → mean.

A → sequence of n numbers or quantities such that the difference between any two successive terms is a constant. In particular, if a is the first term, the nth term is a + (n - 1)d, where d is the constant. Also called → arithmetic sequence.

→ arithmetic; → progression.

→ arithmetic progression.

→ arithmetic; → sequence.

1) Each of the upper limbs of the human body, especially the part between the → shoulder and the → wrist.
2) The upper limb from the shoulder to the → elbow.
3) A slender part of a structure projecting from a main part, such as a → spiral arm. → Orion Arm; → Perseus Arm; → Scutum-Crux Arm.

M.E. arm, from O.E. earm "arm," from P.Gmc. *armaz (cf. M.Du., Ger. Arm, O.N. armr, O.Fris. erm), from PIE base *ar- "to fit, join;" cf. Mod.Pers. arm, as below.

1) Ârm (Dehxodâ, Steingass) "arm, from the elbow to the shoulder;" Av. arma-, arəmo- "arm;" cf. Ossetic ärm "hand;" Armenian armuku "elbow;" Skt. irma- "arm;" Gk. arthron "a joint;" L. armus "shoulder;" cognate with E. arm, as above.
2) Bâzu, → upper arm.

An ancient instrument, used since ancient times until the Middle ages and later, to determine positions of celestial bodies. It consisted of an assemblage of rings, all circles of the same sphere, designed to represent the positions of the important circles of the celestial sphere.

L. armillarius, from armilla "arm ring, bracelet," from armus "arm" + → sphere.

Zâtolhelaq from Ar. "multi-ringed," from zât "holder, keeper" + helaq "rings," from halqah "ring."

1) An agreement between opposing armies to stop fighting for a particular time, especially in order to discuss possible peace; truce
2) A formal agreement, especially between nations, to end combat.

From Fr. armistice, from L. arma "arms" + -stitium, from sistere "to cause to stand," → solstice.

Nâjangân, literally "state of no war," from nâ- "no, not," → un-, + jang, → war, + -ân suffix of time and place.

The → peak luminosity of a → Type Ia supernova is proportional to the rate of → radioactive decay and hence directly proportional to the mass of ⁵⁶Ni.

Arnett, W. D. 1982, ApJ, 253, 785; → rule.

Chemistry: Of, relating to, or containing the six-carbon ring typical of the benzene (C₆H₆) series and related organic groups.

M.E. aromatyk, from M.Fr. aromatique, from L. aromaticus, from Gk. aromatikos, from aroma "seasoning, sweet spice," of unknown origin.

An organic compound which contains benzene rings in its structure. The simplest is therefore benzene (C₆H₆). Aromatic compounds have a planar ring of atoms linked by alternate single and double bounds.

→ aromatic; → compound.

A family of strong infrared emission bands at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 μm which are widely observed in a large variety of objects, such as → H II regions, → reflection nebulae, → planetary nebulae, and the → diffuse interstellar medium of our galaxy and other galaxies. Solar system objects, such as carbonaceous → meteorites and → interplanetary dust particles are also known to display these features. They are suggested to be due to → polycyclic aromatic hydrocarbons.

→ aromatic; → infrared; → band.

1) To set in a rank or row. To put in order.
2) Music: To adapt for other instruments or voices.

From M.E. arayngen, from M.Fr. arangier, from O.Fr. arengier, from a- "to," → ad-, + rangier "set in a row," from rang, → rank.

Rezgidan "to set in a row," from Lori rezg "row," related to râst, → right, Av. rāz- "to direct, draw a line;" probably ultimately from Proto-Ir. *Hrazaka- "row."

The act of arranging or being arranged. Result or manner of arranging.

Verbal noun of → arrange.

1) A system of telescopes coupled together, using → interferometric techniques, to increase the angular resolution or the sensitivity.
2) A two-dimensional detector comprising a large number of identical, individual detectors that can be used simultaneously, e.g. a → CCD.
3) A series of numbers or symbols arranged in some geometric pattern, as in a matrix.

Array, from M.E. arraien, from Anglo-Norman arraier, from V.L. *arredare.

Ârast "set in order," from ârastan, ârâstan "to set in order," Mid.Pers. ârây-, ârâstan, from â- + Av. râd- "to make ready, prepare;" PIE *ar- "to fit together."

An important relationship in physical chemistry that combines the concepts of → activation energy and the → Maxwell-Boltzmann distribution law. It is expressed by: k = Ae^-E_a/(RT), where k is the chemical → reaction rate, E_a is the activation energy, R is the → gas constant, and T is → temperature.

Named for Svante Arrhenius (1859-1927), Swedish chemist and physicist who suggested the relationship in 1889.

The precise time at which the gamma burst photons hit a detector. Measuring the time difference between the arrival time of the photons at different telescopes separated by known distances permits to determine the burst direction.

Arrival, n. from arrive + → -al. Arrive, from O.Fr. ariver "to come to land," from V.L. *arripare "to touch the shore," from L. ad ripam "to the shore," from → ad "to" + ripa "shore;" → time.

Zamân, → time; raseš n. from rasidan "to arrive," Mid.Pers. rasitan, O.Pers./Av. rasa- present stem of ar- "to move, go or come toward," cf. Skt. ar-, rcchati.

A slender, straight, generally pointed missile or weapon made to be shot from a bow and equipped with feathers at the end of the shaft near the → nock, for controlling flight (Dictionary.com). → Sagitta.

M.E. arewe, arwe, O.E. earh, possibly borrowed from O.N. ör; ultimately from PIE *arku- "bow and/or arrow," → arc.

Peykân "arrow, javelin" (cognate with afkan-, afkandan "to throw, cast away," parâkan-, parâkandan "to scatter, to disperse"), ultimately from Proto-Iranian *paiti-kan- "to throw against," from *paiti- "against, opposite, back" (cf. Mod.Pers. pâd- "against, contrary to;" Mid.Pers. pât-; O.Pers. paity "against, back, opposite to, toward, face to face, in front of;" Av. paiti; Skt. práti "toward, against, again, back, in return, opposite;" Pali pati-; Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + *kan- "to throw."

A silver-gray black metallic → chemical element which is very brittle; symbol As. → Atomic number 33; → atomic weight 74.9216; → boiling point 613.0 °C (sublimation); → valence -3, 0, +3, or +5. The uncombined element is not considered poisonous, but many of its compounds are extremely so, and are used in medicine and for destroying pests. Its longest-lived radioactive → isotope, ⁷³As, has a → half-life of 80.3 days.

M.E. arsenik, from O.Fr. arsenic, from L. arsenicum, from Gk. arsenikon "arsenic," adapted from Syriac (al) zarniqa "arsenic," from Mid.Pers. zarnik "arsenic," literally "gold-colored," probably because of the lemon-yellow color of arsenic trisulphide (Mod.Pers. zarnix, zarni "arsenic"), from zarr, zar "gold" (+ -ik→ -ic); Av. zaranya-, zarənu- "gold;" O.Pers. daraniya- "gold;" cf. Skt. hiranya- "gold;" also Av. zaray-, zairi- "yellow, green;" Mod.Pers. zard "yellow;" Skt. hari- "yellow, green;" Gk. khloe literally "young green shoot;" L. helvus "yellowish, bay;" Rus. zeltyj "yellow;" P.Gmc. *gelwaz; Du. geel; Ger. gelb; E. yellow.

Ârsenik, loan from Fr., as above.

The process or product of human activity which is the expression of creativity and/or imagination that appeals to the senses or emotions.

From O.Fr. art, from L. artem, (nominative ars) "art, skill, craft;" from PIE base *ar- "to fit, join;" cf. Mod.Pers. arm "arm, from the elbow to the shoulder;" Av. arma-, arəmo- "arm;" Skt. irma- "arm;" Gk. arthron "a joint;" L. armus "shoulder."

Honar, from Mid.Pers. hunar "skill, ability, virtue, manliness;" O.Pers. hūnarā- "abilities, skills;" Av. hunara- "ability, skill"; cf. Skt. sūnára- "powerful, joyous, beautiful;" Proto-Iranian *Hnar- "to be able, strong."