1. [ noun ] (physics) a unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material
Related terms: radioactivity_unit
2. [ noun ] the unit of plane angle adopted under the System 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)
Synonyms: radian
Related terms: angular_unit milliradian
Similar spelling:   raid