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

Everything that exists anywhere; → outer space; → Universe.

M.E., from Gk. kosmos "orderly arrangement."

Keyhân "world," variants geyhân, jahân, giti "world, material world, time," Mid.Pers. gêhân, gêtig, Manichean Mid.Pers. gyh "world," Av. gaeθa- "being, world, matter, mankind", gaya- "life, manner of living," root gay- "to live" (present tense jiva-), O.Pers. gaiθā- "live-stock," cognate with Skt. jivah "alive, living," Gk. bios "life," L. vivus "living, alive," vita "life;" PIE base *gweie- "to live" (cf. O.E. cwic, "alive;" O.C.S. zivo "to live;" Lith. gyvas "living, alive;" O.Ir. bethu "life," bith "age;" Welsh byd "world"). The Persian terms zistan "to live," zendé "alive," zendegi "life," and jân "vital spirit, soul" belong to this family.

The → tangent of the complement of an arc or angle; abbreviation cot. If θ is an → acute angle of a → right angle, cot θ = (adjacent side)/(opposite side).

→ co-; → tangent.

A soft, usually white fibrous substance like fine wool surrounding the seeds of various tropical and subtropical plants of the mallow family. It is extensively used in making threads, yarns, and fabrics.

M.E. coton, from O.Fr. coton, from O.It. cotone, from Ar. qutn (قطن), perhaps of Egyptian origin.

Panbé "cotton" (dialectal Lori pamma, Kurd. pemû, maybe Tajik, Afqân pakta, pakhta, bakhta, bakta), from Mid.Pers. pambag "cotton," pambagin "made of cotton," perhaps loaned in Gk. bombux "silk, any silk-like fine fiber;" L. bombyx "silk, cotton," L.L. bombax "cotton," hence O.Fr. bombace "cotton, cotton wadding," E. bombast "cotton wool; inflated language."

An → optical system in which the → beam of light from the → primary mirror is reflected down through the instrument's → polar axis by a path bent like an → elbow. Since the focus remains fixed with respect to the Earth, light can be analyzed with permanently installed instruments. In addition long → focal lengths allow higher → spectral dispersions.

From Fr. coudé "elbowed," from coude "elbow," L. cubitus; → focus.

Kânun, → focus; ârenjvâr "elbow-like," → elbow.

In fluid dynamics, the motion of an → incompressible → laminar flow passing between two parallel plates, when the upper plate is moving with some velocity while the lower one is stationary. The flow is driven owing to the fluid → viscosity and the applied pressure gradient parallel to the plates. See also → Taylor-Couette flow.

Named after Maurice Marie Alfred Couette (1858-1943), a French physicist who dealt mainly with fluid mechanics; → flow

A device consisting of two vertical coaxial cylinders and a fluid filling the volume between the cylinders and used for measuring the viscosity of the fluid. The inner cylinder is stationary while the outer cylinder rotates. The amount of shear stress produced owing to rotation is directly proportional to the viscosity of the fluid.

→ Couette flow; → viscometer.

In fluid mechanics, the motion of a fluid between two concentric cylinders when one or both of the cylinders rotate.

→ Couette flow; Geoffrey Ingram Taylor (1886-1975), British physicist; → flow.

The unit of → electric charge in the → mks system, equal to the quantity of charge transferred in one second by a steady current of one → ampere. One coulomb represents a charge of approximately 6.241 506 × 10¹⁸ → electrons. Compared with the charge unit in the → cgs system, 1 C = 2.998 × 10⁹ → esu.

Named after the French physicist Charles Augustin de Coulomb (1736-1806), who pioneered research into magnetism and electricity.

The energy barrier due to electrostatic interaction that two nuclei (for example two protons) need to overcome so they can get close enough to undergo nuclear fusion (to form a helium).

→ coulomb; → barrier.

A particle → collision where the dominant force is described by → Coulomb's law. The collision results in deflections of the particles away from their initial paths.

→ coulomb; → collision.

The → potential energy from which derives the repulsive electrostatic force between two → charged particles. For example, the Coulomb energy between two protons is e²/r ~ 0.5 MeV, which is small compared with the average → binding energy per particle (~ 8 Mev). However the Coulomb repulsion becomes important for heavy nuclei. The total Coulomb energy of a nucleus is given by: (3/5) Z(Z - 1)e²/R, where Z is the → atomic number, e the charge, and R the nuclear radius. Since R ∝ A^1/3 and Z is roughly proportional to A, the Coulomb energy is roughly proportional to A^5/3. On the other hand, the total binding energy is proportional to A, which means that the relative importance of the repulsive electrostatic energy increases with increasing mass number as A^2/3.

→ coulomb; → energy.

The transition to a higher → energy level than → ground state undergone by an atomic nucleus when a → charged particle of appropriate energy moves past it.

→ coulomb; → excitation.

An attractive or repulsive → electrostatic force between objects bearing electric charge, as described by → Coulomb's law. If the charges are of opposite sign, then the force is attractive; if thy are of the same sign, the force is repulsive.

→ Coulomb; → force.

The optimum → gauge for steady fields, defined by: ∇.A = 0, where A is the → magnetic vector potential. Also called transverse gauge.

→ Coulomb; → gauge.

The reciprocal force between two or more → charged particles according to → Coulomb's law.

→ coulomb; → interaction.

The repulsive interaction due to the → Coulomb energy between two ions. If the ionic charge is Z, then the Coulomb potential energy is Z²e²/a, where a is some typical separation between the ions. The Coulomb pressure is expected to become important when the ratio Γ_C = Z²e²/akT is much larger than 1. In that case, Coulomb effects dominate those of → thermal agitation and the gas settles down into a → crystal.

→ Coulomb; → pressure.

The electrical force between two charged objects is directly proportional to the product of the quantity of charge on the objects and inversely proportional to the square of the separation distance between the two objects

→ coulomb; → law.

An assembly of persons summoned or convened for consultation, deliberation, or advice (Dictionary.com).

From M.E. counseil, conseil, from Anglo-Norman cuncile, from O.Fr. concile "assembly; council meeting," from L. concilium "a meeting, a gathering of people," from → com- "together" + calere "to call, announce" + -ium.

Hâšin, literally "sitting together" (on the model of Skt. samsad- "sitting together, assembly"), from prefix hâ-, variant of ham- "together," → com-, + (ne)šin, present stem of nešastan "to sit;" Mid.Pers. nišin-, nišastan "to sit;" O.Pers. (ni)šâd- "to establish;" Av. hiδ- "to sit;" cf. Skt. sad- "to sit," sidati "sits;" Gk. ezesthai "to sit," L. sedere "to sit;" Goth. sitan, Ger. sitzen, E. (to) sit; PIE root *sed- "to sit."

1) (v.) To enumerate; reckon up; calculate; compute.
2) (n.) A single ionizing event registered by a device such as a → Geiger counter.
The indication of the total number of ionizing events registered by a device.

From O.Fr. conter "add up," from L. computare, → compute.

Šomârdan, from 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-, cf. Skt. smar- "to remember, become aware," smarati "he remembers," L. memor, memoria, Gk. mermera "care," merimna "anxious thought, sorrow," martyr "witness."

1) The backward counting in fixed time units from the initiation of a project, as a rocket launching, with the moment of firing designated as zero.
2) The final preparations made during this period (Dictionary.com).

→ count; → down.