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

Math.: The fact that at least one → solution exists for a given → problem.

→ exist; → -ence.

Math: The question of whether a → solution to a given → problem exists.

→ existence; → problem.

Math.: An → argument that establishes an → existence theorem.

→ existence; → proof.

Math: A theorem that asserts the existence of at least one object, such as the → solution to a → problem or → equation.

→ existence; → theorem.

Existing; having existence.

→ exist.

1) Of or relating to → existence, especially  human existence.
2) Philo.:  Pertaining to what exists, and is thus known by experience rather  than reason; empirical as opposed to theoretical.
3) Logic: Denoting or relating to a → formula or → proposition asserting the existence of at least one object fulfilling a given condition; containing an → existential quantifier.
4) Of or relating to → existentialism (Dictionary.com).

From L.L. existentialis, → existence, → -al.

Hastiyâl, from hasti, → existence, + -al a suffix of attributes forming adjectives that often become nouns, in this case preferred to -i because hasti ends in -i, → -al.

A symbol of → predicate logic which expresses that the statements within its scope are → true for at least one instance of something. The symbol ∃ is used as the existential quantifier. Existential quantifiers are normally used in logic in → conjunction with → predicate symbols, which say something about a → variable or → constant, in this case the variable being quantified (→ quantify, → quantification).

→ existential; → quantifier.

A philosophical attitude associated especially with Heidegger, Jaspers, Marcel, and  Sartre, and opposed to → rationalism and  → empiricism, that stresses the individual's  unique position as a self-determining agent responsible for the authenticity of his or  her choices (Dictionary.com).

→ existential; → -ism.

An advocate of → existentialism.

→ existential; → -ist.

To stretch out; draw out to the full length; to enlarge the scope of; to increase the length or duration of.

From O.Fr. estendre, from L. extendere "stretch out," from → ex- "out" + tendere "to stretch," see below.

Ostanidan, from os-, → ex- + tanidan as in Av. ustāna- "stretched out" (ustāna-zasta- "with outstretched hands"), cf. Skt. uttāná- "stretched out, spread out." Mod.Pers. tanidan "to spin, twist, weave;" Mid.Pers. tanitan, from Av. tan- to stretch, extend;" cf. Skt. tan- to stretch, extend," tanoti "stretches," tantram "loom;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" PIE base *ten- "to stretch."

An object whose angular size exceeds the resolution of the instrument used to observe it.

→ extended; → object.

In radio astronomy, a source whose angular extent could be measured, as distinguished from a point source.

→ extended; → source.

1) An act or instance of extending; the state of being extended.
2) Physics: That property of a body by which it occupies space.
3) Math.: A field F is said to be an extension of a field K if K is a subfield of F.
4) Logic: The sum of all individuals or objects to which the comprehension of a term is applied. For example, the extension of the term "dog" is the set of all (past, present and future) dogs in the world.

Verbal noun of → extend.

The range over which a thing extends; length, area, volume, or scope.

→ extension.

1) To attach firmly or securely in place; fix securely to something else.
2) To make secure, as an article of dress with buttons, clasps, etc., or a door with a lock, bolt, etc. (Dictionary.com).

From M.E. fastenen, from O.E. fæstnian; cognate with O.Fris. festnia "to make firm, bind fast," O.Sax. fastnon, O.H.G. fastnion, O.N. fastna "to pledge, betroth."

Darizidan, from Proto-Ir. *darz- "to attach, fasten;" cf. Av. darəz- "to attach;" Mid.Pers. handarz "advice, order, command," drz- "to fasten;" Mod.Pers. andarz "advice; testament," darzan "needle," darzi "tailor," razé (with elimination of the initial phoneme) "a ring or staple used to fasten a door," padarzé "a wrapper in which clothes are folded up;" cf. Skt. drah- "to fix, make firm;" Gk. drassomai "I take hold of, grasp;" Russ. deržat' "to hold, keep" (Cheung 2007).

1) The energy that an object possesses because of its position in a → gravitational field, especially an object near the surface of the Earth where the → gravitational acceleration can be assumed to be constant, at about 9.8 m s^-2.
2) In a two body system. It is the amount of work done in bringing the mass m to the distance R from M: E_P = -GMm/R, where G is the → gravitational constant.
3) For a uniform sphere. It is E_P = -(3/5)GM²/R, where G is the gravitational constant and M is the mass contained in the sphere of radius R.

→ gravitational; → potential; → energy.

→ gravity darkening.

→ gravity; → brightening.

The discrepancy between the value of the → Hubble-Lemaitre constant inferred from a ΛCDM fit (→ Lambda cold dark matter model) to the → cosmic microwave background (CMB) and local measurements. The Universe appears to be expanding much faster now than predicted even with our latest understanding of its initial conditions and contents. Based on the → Hubble Space Telescope observations, the Hubble-Lemaitre constant is very recently estimated to be 74.03 km s^-1 Mpc^-1. This value indicates that the Universe is expanding at a rate about 9% faster than that implied by the → Planck satellite's observations of the → early Universe, which give a value for the Hubble constant of 67.4 km s^-1 Mpc^-1. For discussion, see D'Arcy Kenworthy et al. (2019, ApJ 875, 145).

→ Hubble-Lamaitre constant; → tension.

In a → right triangle, the side opposite to the right angle.

L.L. hypotenusa, from Gk. hypoteinousa "stretching under" (the right angle), from hypoteinein, from → hypo- "under" + teinein "to stretch," → tension.

Vatar loan from Ar.

Device that produces an observable image that is brighter at output than the image at input.

→ image; → intensifier.