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

A coherent and rationalized system of units, in common use in physics since 1969. The seven basic units are the → meter, the → kilogram, the → second, the → ampere, the → kelvin, the → mole, and the → candela. Same as international system of units.

SI, from Fr. Système Internationale d'unités; → unit.

A measure of the flux of neutrinos from the Sun reaching the Earth. 1 SNU is equal to 10^-36 solar neutrinos captured per target atom per second.

→ solar; → neutrino; → unit.

A quantity or dimension adopted as a standard of measurement.
Math.: The lowest positive natural number.
The first digit to the left of the decimal point in decimal notation, representing a whole number less than ten.
An element in a ring that has a multiplicative inverse.

Back formation from → unity.

Yekâ, yekân, from yek, → one.

A vector of length 1, also called a direction vector.

→ unit; → vector.

1) The condition of being → unitary.
2) → quantum unitarity.

→ unitary; → -ity.

1) Of or pertaining to a unit or units; having the indivisible character of a unit.
2) Math.: An → operator  U satisfying the relations: U⁺ U = 1, U U⁺ = 1, where U⁺ is the → adjoint .

→ unit + -ary.

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.