Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A unit of angular measure equal to the angle subtended at the center of a circle by an arc equal in length to the radius of the circle, approximately 57°17′44.6″.

from The Century Dictionary.

  • noun The angle subtended at the center of a circle by an are equal in length to the radius. Also called the unit angle in circular measure. It is equal to 57° 17′ 44″. 80625 nearly.
  • noun A unit of angular velocity equivalent, approximately, to 0.15916 revolutions per second, or, strictly, to revolutions per second: in full, radian per second.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Math.) An arc of a circle which is equal to the radius, or the angle measured by such an arc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun geometry 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

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • 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)

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[radi(us) + –an.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From radi(us) + -an

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Examples

  • Light en - ergy gathered by the sheaths was relayed by lines called radian draws.

    Ilse Witch Brooks, Terry 2000

  • A radian is a measurement used to describe angles.

    Francis Shanahan[.com] 2009

  • A radian is the equivalent of (a) 2 angular degrees (b) 1/(2) of the angle comprising a full circle (c) the circumference of a unit circle (d) 1 = 4 of the angle comprising a full circle

    Recently Uploaded Slideshows 2009

  • When to use "radian" mode in casio scientific calculator fx-85ms.? what is difference between methematics and logic or arthematics? true/false For any two subsets A, B in a vector space [A intersection B] = [A] intersection

    Yahoo! Answers: Latest Questions 2010

  • One radian of phase, symbolized rad (although you can write out the whole word '' radian ''), is equal to about

    Recently Uploaded Slideshows 2009

  • Your symplectic one, though, if it has made an error of one A.U. in its position, will put it one radian ahead or behind in its orbit, but still in its correct orbit.

    This "Fix" in the GISS Code « Climate Audit 2007

  • As a result, the radian/degree error was quickly diagnosed and known long before any potential use of these results for policy purposes.

    Earth's climate crashes in 2013 « Climate Audit 2006

  • You'd have to have a pretty accurate launcher radian to assure the launch elevation was precisely the same as last time.

    Did You Know? Garry 2006

  • Re #19C: I had nothing to do with the radian/degree thing, although they all pretend that.

    Roll Over, Preisendorfer « Climate Audit 2005

  • Spanner Frew yelled something down to one of the Rovers amidships, and the crewman waved back, moving to tighten a radian draw.

    Morgawr Brooks, Terry 2002

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