noun
solid angle
Technical term in geometry and physics; the three-dimensional analog of a planar angle, measured in steradians.
立体角はステラジアンで表される。
Solid angle is expressed in steradians.
平面角 is a planar angle (measured in radians), while 立体角 is a solid angle (measured in steradians).
Compound of 立体 (solid, three-dimensional) and 角 (angle).