stə̇ˈrādēən noun
also sterad ˈsteˌrad, ˈstiˌr-
( -s )
Etymology: steradian from stere- + radian; sterad short for steradian
: a unit of measure of solid angles that is expressed as the solid angle subtended at the center of the sphere by a portion of the surface whose area is equal to the square of the radius of the sphere