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steradian

[ stuh-rey-dee-uhn ]
/ stəˈreɪ di ən /
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noun Geometry.
a solid angle at the center of a sphere subtending a section on the surface equal in area to the square of the radius of the sphere. Abbreviation: sr
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Origin of steradian

First recorded in 1880–85; ste(reo)- + radian
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

British Dictionary definitions for steradian

steradian
/ (stəˈreɪdɪən) /

noun
an SI unit of solid angle; the angle that, having its vertex in the centre of a sphere, cuts off an area of the surface of the sphere equal to the square of the length of the radiusSymbol: sr

Word Origin for steradian

C19: from stereo- + radian
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for steradian

steradian
[ stĭ-rādē-ən ]

A unitless measure of solid angles. A solid angle projecting from the center of a sphere and cutting its surface has a measure ofsr2 steradians, where s is the surface area of the sphere cut out by the solid angle, and r is the radius of the sphere. See also radian.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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