Noun has 2 senses

• rad(n = noun.quantity) - a unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material;


• rad(n = noun.quantity) radian - the unit of plane angle adopted under the Systeme International d'Unites; equal to the angle at the center of a circle subtended by an arc equal in length to the radius (approximately 57.295 degrees);