endian: denoting or relating to two systems of ordering data, in which the most   significant unit is put either first or last.  
radian: is a pure measure based on the Radius of the circle. To go from radians to   degrees: multiply by 180, divide by π. To go from degrees to radians: multiply by π,   divide by 180   
float Degrees = Radians * 180.0f / 3.14159265359f  
float Radian = Degrees * 3.14159265359f / 180.0f  
The C language uses radians instead of degrees when calculating angles. Humans should   use radians as well, as they're logical and easy to work with (radians, not humans).