The grad is a unit of plane angle, equivalent to 1/400 of a full circle, dividing a right angle in 100. It is also known as gon, grade, or gradian (not to be confused with gradient). One grad equals 9/10 of a degree or π/200 of a radian. In continental Europe, the term centigrade was in use for one hundredth of a grade. This was one reason for the adoption of the term Celsius for the unit of temperature.