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

A charge or claim that someone has done something illegal or wrong; the action or process of accusing someone (OxfordDictionaries.com).

→ accuse; → -tion.

1) → accusative case.
2) → accusatory.

M.E., from M.Fr., from L. accusativus, from ac-, → ad-, + -cusativus, combining form of causativus, → causative, a loan-translation of Gk. aitiatike, in the sense of pointing to the origin or cause, accusing.

1) Kondâri, i.e. → objective case.
2) → accusatory.

The → grammatical case of a noun in some languages (such as Greek, Latin, G erman, Russian, Old Persian, Avestan, or Sanskrit), which shows that the noun is the → direct object of a → verb or a → preposition.

→ accusative; → case.

Containing an accusation; accusing (Dictionary.com).

→ accuse; → -tion.

To charge with the fault, offense, or crime (Dictionary.com).

M.E. ac(c)usen, from O.Fr. acuser "to accuse, indict, blame," earlier "announce, report, disclose," from L. accusare "to call to account," from → ad- "to, toward, at, with regard to" + causari "give as a cause or motive," from causa "reason," → cause.

Mârzidan, from (Lâr, Gerâsh) mârz, (Farâmarzân) morz "blame, reproach, accusation," maybe ultimately from Proto-Ir. *marc- "to destroy, damage;" cf. Av. mərənc- "to destroy," (+ *para-) "to damage, injure," (+ *ui-) "to ruin, spoil;" Mid.Pers. mwlncyn- / murnjên- "to destroy;" Khotanese mulch- "to cause to miscarry" (Cheung 2007).

A person or persons charged in a court of law with a crime, offense, etc.

→ accuse; → -tion.

A person who accuses, especially in a court of law.

→ accuse; → -tion.

The brightest star in the constellation → Eridanus. A → subgiant of → spectral type B5; apparent visual magnitude 0.5, about 140 → light-years distant (other names: HR 472, HD 10144). Recent interferometric observations show it to have a flattened shape imposed by fast rotation.

Achernar, from Ar. Axir an-Nahr "end of the river," from axir "end" + nahr "river".

Âxer-e nahr, from Axir an-Nahr.
Rudpâyân "river's end," from rud "river," → Eridanus, + pâyân "end".

A class of → stony meteorites that lack → chondrules. They are made of rock that has crystallized from a molten state. Achondrites are relatively rare, accounting for about 8% of all meteorite falls.

Achondrite, from Gk. prefix a- (an- before stems beginning with a vowel or h) "not, without, lacking" + Gk. chondrite, from chondr-, from chondros "grain," + affix -ite.

Of or relating to an optical system which is capable of transmitting light without decomposing it into constituent colors.

→ a-; → chromatic.

Lens (or combination of lenses) that brings different wavelengths within a ray of light to a single focus, thus overcoming chromatic aberration.

→ achromatic; → lens.

A substance that releases hydrogen ions to form a solution with a pH of less than 7, reacts with a base to form a salt, and turns blue litmus red.

From Fr. acide, from L. acidus "sour," adj. of state from acere "to be sour," acer "sharp, pungent, bitter;" from PIE base *ak- "sharp, pointed."

Being or containing an acid; of a solution having an excess of hydrogen atoms (having a → pH of less than 7).

→ acid; → -ic.

1) To admit to be real or true; recognize the existence, truth, or fact of.
2) To recognize the authority, validity, or claims of.
3) To show or express appreciation or gratitude for (Dictionary.com).

A blend of M.E aknow "admit or show one's knowledge" (from O.E. oncnawan "understand") and M.E. knowlechen "to admit."

Âdânidan, from âdân, from prefix â- + dân present stem of dânestan, → know; cf. Sogd. âzân, azân "to acknowledge, to confess," from prefixed zân, variant of dân.

1) Recognition of the existence or truth of something.
2) An expression of appreciation (Dictionary.com).

→ acknowledge; → -ment.

Pertaining to the sense of hearing, or to → sound waves.

→ acoustics.

One of several peaks appearing in the → CMB angular power spectrum of the → cosmic microwave background radiation which are ripples left by acoustic oscillations of the plasma-radiation fluid in the early Universe (→ baryon acoustic oscillations). When the Universe was small and very hot, the free electron density was so high that photons could not propagate freely without being scattered by electrons. Ionized matter, electrons and radiation formed a single fluid, with the inertia provided by the baryons and the radiation pressure given by the photons.

→ acoustic; → peak.

Same as → sound pressure.

→ acoustic; → pressure.

A type of → longitudinal wave that consists of mechanical → vibrations of small → amplitude propagated in an → elastic medium. Acoustic waves exhibit phenomena like → diffraction, → reflection, and → interference, but not → polarization. Also called → sonic and → sound waves. See also → acoustic wave equation. The branch of physics concerned with the properties of sonic waves is called → acoustics.

→ acoustic; → wave.

A → differential equation that describes the time evolution of the → scalar potential of the field φ. It is expressed by: ∇²φ = (1/c²)∂²φ/∂t², where c is → velocity of → longitudinal waves and ∇² is the → Laplacian operator.

→ acoustic; → wave; → equation.