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

Of a gas, the ratio of its → specific heat at constant pressure to its specific heat at constant volume: γ = C_P/ C_V.

→ adiabatic; → index.

The assumption whereby the density fluctuations in the very → early Universe would be produced by compressing or decompressing of all components of a homogeneous Universe. The adiabatic initial conditions lead to coherent oscillations in the form of peaks in the → temperature anisotropy spectrum. See also → acoustic peak, → baryon acoustic oscillation.

→ adiabatic; → initial; → condition.

Same as the → Sedov-Taylor phase.

→ adiabatic; → phase.

A → thermodynamic process in which no → heat is supplied to or rejected from a system. → polytropic process.

→ adiabatic, → process.

A → shock wave without → radiative cooling. The term "adiabatic" refers to the fact that no → heat is removed during shock.

→ adiabatic; → shock.

The temperature gradient defining the → radiative equilibrium condition in a region. It is expressed as: dT/dr = (1 - 1/ γ)((T / P)(dP / dr), where T and P are temperature and pressure, dT / dr and dP / dr temperature and pressure gradients respectively, and γ = C_P / C_V. For radiative equilibrium to be stable against → convection, the actual temperature gradient must be less than the adiabatic temperature gradient, i.e. |dT /dr|_rad < |dT /dr|_ad. See also → Schwarzschild's criterion.

→ adiabatic; → temperature; → gradient.

In grammar, a word that qualifies, describes, or quantifies a noun.

M.E., from O.Fr. adjectif, from L. adjectivum "that is added to (the noun)," neuter of adjectivus "added," from p.p. of adicere "to throw or place (a thing) near," from → ad- "to" + iacere "to throw," → jet.

Zâbé, from zâb "attribute, quality" (Dehxodâ); probably related to zib "beauty, adornment," zibâ "beautiful, adorned," zivar "ornament," zab "easy; gratis; right, direct;" from Proto-Ir. *zai- "to adorn, to equip."

1) To be close to or in contact with.
2) To attach or append (dictionary.com).

M.E., from O.Fr. ajoindre"join together, unite," from L. adjungere "fasten on, harness, join to," from → ad- "to" + jungere "to bind together," cognate with → yoke.

Âbandidan, âbanidan, from prefix â- + band, vand, bastan, in dialects contracted to ban-, van- "to bind, attach," → band, + -idan infinitive suffix.

Literally "joined to." → adjoint matrix.

→ adjoin.

The → transpose of a → matrix in which each → element is replaced by its → cofactor. Same as → conjugate transpose and → Hermitian conjugate.

→ adjoint; → matrix.

1) To change (something) so that it fits, corresponds, or conforms; adapt; accommodate.
2) To put in good working order; regulate; bring to a proper state or position (Dictionary.com).

M.E. ajusten, "to correct, remedy; arrange, settle, compose," from M.Fr. adjuster, O.Fr. ajouter "to join," from L.L. adjuxtare "to bring near," from L. → ad- "to" + juxta "next," related to jungere "to join," from PIE *yeug- "to join," → conjugate, akin to E. → yoke.

Barjutidan, from prefix bar-, → on-, + Kurd. Soriani jut, jot "pair, couple, twin," Aftari jot "yoke," classical Pers. yuq, → yoke.

The act of adjusting.

Verbal noun of → adjust.

1) To choose or take as one's own; make one's own by selection or assent.
2) To take and rear (the child of other parents) as one's own child, specifically by a formal legal act.
3) To vote to accept (Dictionary.com).

M.E., from M.Fr. adopter, from L. adoptare, from → ad- + optare, → opt.

Baroptidan, on the model of bargozidan "to choose," from bar- "on, up, upon, in," → on-, + optidan, → opt.

The act of adopting. The state of being adopted.

→ adopt; → -tion.

Of or involving adoption. Acquired or related by adoption.

→ adopt; → -ive.

The second innermost known satellite of Jupiter, whose orbit is situated at a distance of about 129 000 km from the planet, and its orbital period is of 0.298 days; also known as Jupiter XV. Adrastea is 25 x 20 x 15 km in size.

In Gk. mythology, Adrastea was the daughter of Zeus and Ananke and the distributor of reward and punishments.

To take up and hold another substance on the surface.

→ adsorption.

1) A material that can hold or condense molecules of another substance on its surface by adsorption.
2) Relating to or capable of adsorption.

From → adsorb + →-ent.

Baršamandé, from baršamidan, → adsorb, + -andé.

A process in which a layer of atoms or molecules of one substance forms on the surface of a solid or liquid. → absorption, → desorption, → sorption.

Adsorption from ad- "to" + sorption, from L. sorbere "to suck," → absorption.

Baršam, from bar- "on, upon" + šam "to drink, sip," → absorption.

1) A person who is fully grown or developed or of age.
2) Having attained full size and strength; grown up; mature. A person who has attained the age of maturity as specified by law (Dictionary.com).

From L. adultus "grown up, mature, adult, ripe," p.p. of adolescere "to grow up, mature," from → ad- "to" + alescere "be nourished," from alere "to nourish."

Bornâ, from Mid.Pers. purnây- "adult;" Av. pərənāyu- "adult, old;" (Baluchi warnâ "adolescent"), literally "of full age," from pərəna-, → full, + āyu- "age," → aeon.