Gradian
The gradian is a unit of measurement of an angle, equivalent to 1⁄400 of a turn,9⁄10 of a degree or π⁄200 of a radian.
It is also known as gon (from Greek γωνία/gōnía for angle), grad, or grade. In continental Europe, the French term centigrade was in use for one hundredth of a grad. This was one reason for the adoption of the term Celsius to replace centigrade as the name of the temperature scale.
History
The unit originated in France as the grade, along with the metric system, hence it is occasionally referred to a "metric degree". Due to confusion with existing grad(e) units of northern Europe, the name gon was later adopted, first in those regions, later as the international standard. In German, the unit was formerly also called Neugrad (new degree), likewise Nygrad in Swedish, Danish and Norwegian (also Gradian), and Nýgráða in Icelandic.
Although attempts at a general introduction were made, the unit was only adopted in some countries and for specialised areas such as surveying, mining and geology. The French artillery has used the grad for decades. The degree, 1⁄360 of a circle, or the mathematically more convenient radian, 1⁄(2π) of a circle (used in the SI system of units) are generally used instead.
