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rad

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Mathematics.
  1. radian; radians.
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rad1

[rad]
noun Physics.
  1. a standard unit of absorbed dose of radiation equal to 0.01 gray2.
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Compare dose(def 4a).

Origin of rad1

First recorded in 1915–20; shortened form of radiation

rad2

[rad]
noun
  1. Informal. radical.
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adjective
  1. Slang. fine; wonderful.
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Origin of rad2

by shortening of radical

rad.

Mathematics.
  1. radical.
  2. radix.
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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018


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British Dictionary definitions for rad

rad1

noun
  1. a former unit of absorbed ionizing radiation dose equivalent to an energy absorption per unit mass of 0.01 joule per kilogram of irradiated material. 1 rad is equivalent to 0.01 gray
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Word Origin

C20: shortened from radiation

rad2

symbol for
  1. radian
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rad.

abbreviation for
  1. radical
  2. radius
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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

Word Origin and History for rad

"x-ray dose unit," 1918, shortened form of radiation (q.v.). As shortened form of radical (n.), it is attested in political slang from 1820. Teen slang sense of "extraordinary, wonderful" is from late 1970s (see radical (adj.)).

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Online Etymology Dictionary, © 2010 Douglas Harper

rad in Science

rad

[răd]
  1. A unit used to measure energy absorbed by a material from radiation. One rad is equal to 100 ergs per gram of material. Many scientists now measure this energy in grays rather than in rads.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

rad in Culture

rad

An acronym for radiation absorbed dose. A unit of energy absorbed from ionizing radiation.

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The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.