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

1) Beyond what is usual, ordinary, regular, or established.
2) Exceptional in character, amount, extent, degree, etc. (Dictionary.com). → unordinary.

→ extra-; → ordinary.

When a beam of → unpolarized light is incident on a → doubly refracting crystal, there will be two refracted rays. The ray for which → Snell's law does not hold.

→ extraordinary; → ray.

Usual; normal. → ordinary ray; → ordinary year.

M.E. ordinarie, from O.Fr. ordinarie, from L. ordinarius "regular, usual, orderly," from ordo (genitive ordinis) "order" + -arius-ary.

Šunik "ordinary," from Mid.Pers. šônik, šônig "ordinary, customary," from šôn "kind, manner, sort, way" + -ik, → -ic.

A → differential equation in which the unknown function depends on only one → independent variable, as contrasted with a → partial differential equation.

→ ordinary; → differential; → equation.

The point M₀(x₀,y₀) of the curve F(x,y) = 0, where at least one of the partial derivatives ∂F/∂x and ∂F/∂y does not vanish. → singular point

→ ordinary; → point.

The ray that has an → isotropic speed in a → doubly refracting crystal. It obeys → Snell's law upon refraction at the crystal surface. See also → extraordinary ray

→ ordinary; → ray.

A → calendar year that contains 365 days and therefore is not a → leap year.

→ ordinary; → year.

Uncommon, unusual. → extraordinary.

→ un-; → ordinary.