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

The set of n × n unitary matrices (→ unitary matrix).

→ unitary; → group.

A square matrix whose inverse equals its adjoint.

→ unitary; → matrix.

A linear operator whose inverse is its → adjoint. In addition to → Hermitian operators, unitary operators constitute a fundamentally important class of quantum-mechanical operators.

→ unitary; → operator.

A transformation whose reciprocal is equal to its Hermitian conjugate.

→ unitary; → transformation.

To join, combine, or incorporate so as to form a single whole or unit.

M.E. uniten, from L. unitus, p.p. of unire "to unite," from unus, → one.

Âyekidan, from â- nuance/strengthening prefix + yek, → one, + -idan infinitive suffix; ham-yekidan, from ham- "together," → syn-, + yekidan.

Formed by or resulting from the union of two or more persons or things.

P.p. of → unite.

The state or condition of being one.
Math.: One.

M.E. unite, from O.Fr., from L. unitatem "oneness, sameness, agreement," from unus, → one.

Yeki, noun from yek, → one.

Statistics: Involving only one variable.

→ uni-; → variate.

A sequence of measurements of the same variable collected over time. Most often, the measurements are made at regular time intervals.

→ univariate; → time; → series.

1a) Of, pertaining to, or characteristic of all or the whole; relating to, affecting, or including everyone in a group or situation.
1b) Of or pertaining to the → Universe, all nature, or all existing things.
2) A trait, characteristic, or property, as distinguished from a particular individual or event, that can be possessed in common, as the care of a mother for her young (Dictionary.com).
See also: → Coordinated Universal Time, → universal astrolabe, → universal gas constant, → universal IMF, → universal quantifier, → Universal Time.
Related concepts: → all, → general, → omni-, → public, → total.

→ universe; → -al.

An → astrolabe which could be used at any → latitude.

→ universal; → astrolabe.

Same as → gas constant.

→ universal; → gas; → constant.

Same as → canonical IMF.

→ universal; → initial mass function.

A symbol of → predicate logic which expresses that the statements within its scope are → true for everything, or every instance of a specific thing. The symbol ∀ "for all" is used as the universal quantifier. Universal 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.

→ universal; → quantifier.

A measure of time that conforms, within a close approximation, to the mean diurnal motion of the Sun and serves as the basis off all civil timekeeping. The local civil time for a position on the Greenwich meridian.

→ universal; → time.

Sale as → Coordinated Universal Time (UTC).

→ Coordinated Universal Time (UTC).

The character or state of being universal.

→ universal; → -ity.

Same as → weak equivalence principle.

→ universality; → free; → fall.

The hypothesis whereby there exists a universal parent → distribution function which describes the stellar → initial mass function in individual star forming events. A consensus appears to have emerged in the community that the stellar IMF is largely invariant for star formation conditions as are found throughout the Local Group of galaxies at the present time. For details and discussion see Pavel Kroupa (2012), Recent advances on IMF research, arXiv.org/abs/astro-ph/1210.1211, and references therein.

→ universality; → initial mass function.

1) The totality of all matter and energy that exists in the vastness of cosmos whether known to human beings or not. Related concepts: → world, → cosmos, → multiverse.
2a) Math.: A → set made of → subsets that contains all the elements relevant to a particular discussion or problem.
2b) Statistics: The entire population under study.
See also: → all, → general, → omni-, → public, → total.

M.E., from O.Fr. univers, from L. universum "the universe," noun use of neuter of adj. universus "all together," literally "turned into one," from unus, → one, + versus, p.p. of vertere "to turn," akin to Pers. gar-, gardidan "to turn, to change" (Mid.Pers. vartitan; Av. varət- "to turn, revolve;" cf. Skt. vrt- "to turn, roll," vartate "it turns round, rolls;" L. vertere "to turn;" O.H.G. werden "to become;" PIE base *wer- "to turn, bend").

1) Giti "world, material world, time," variants jahân, keyhân, geyhân "world;" Mid.Pers. gêhân "world," gêtig "the material world; wordly;" Av. gaēθā- "being, world, matter, mankind," gaya- "life, manner of living", root gay- "to live" (present tense jiva-), O.Pers. gaiθā- "live-stock," cognate with Skt. jīv- "to live," jīva- "alive, living;" Gk. bios "life," L. vivus "living, alive," vita "life;" PIE base *g^wei- "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 Pers. words zistan "to live," zendé "alive," zendegi "life," and jân "vital spirit, soul; mind" belong to this family.
2) Hargân, from har "every, all, each," → holo-, + -gân suffix forming plural entities, from Mid.Pers. -gânag, -gâna, on the model of hamegân, → public.