In the International System of Units, the derived unit of plane angular measure of angle equal to the angle subtended at the centre of a circle by an arc of its circumference equal in length to the radius of the circle. Symbol: rad
Anything which radiates or emits rays.
A device that lowers engine coolant temperature by conducting heat to the air, through metal fins.
(of buildings) A finned metal fixture that carries hot water or steam in order to heat a room.
A type of antenna.
The distance between the front and rear sights of a firearm.