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Noun: radian  rey-dee-un
  1. The unit of plane angle adopted under the Système International d'Unités; equal to the angle at the centre of a circle subtended by an arc equal in length to the radius (approximately 57.295 degrees)
    "Mathematicians prefer to use radians rather than degrees in many calculations";
    - rad

Derived forms: radians

Type of: angular unit

Encyclopedia: Radian