radian

Từ điển WordNet v3.1 - WordNet Dictionary

noun

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)
• Syn:
rad
• Hypernyms:
angular unit
• Part Meronyms:
milliradian