rad

1
[ rad ]
/ ræd /

noun Physics.

a unit of absorbed dose of radiation equal to 0.01 gray2: not a standard SI unit, the rad is still used, especially in the U.S., but it is increasingly disfavored.

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Origin of rad

1
First recorded in 1915–20; r(adiation) a(bsorbed) d(ose)

Definition for rad (2 of 4)

rad2
[ rad ]
/ ræd /

noun

Informal. a radical, especially a person with extreme views on political and social issues.

adjective, rad·der, rad·dest.

Slang. excellent; wonderful; cool: a high speed, high energy, totally rad racing game.

Origin of rad

2
First recorded in 1820–25 for 1; 1975–80 for 2; shortening of radical

Definition for rad (3 of 4)

rad3
[ rad ]
/ ræd /

abbreviation Mathematics.

radian; radians.

Origin of rad

3
First recorded in 1910–15; shortening

Definition for rad (4 of 4)

rad.

abbreviation Mathematics.

radical.
radix.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

Example sentences from the Web for rad

British Dictionary definitions for rad (1 of 3)

rad1
/ (ræd) /

noun

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

Word Origin for rad

C20: shortened from radiation

British Dictionary definitions for rad (2 of 3)

rad2

symbol for

radian

British Dictionary definitions for rad (3 of 3)

rad.

abbreviation for

radical
radius
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

Medical definitions for rad (1 of 2)

rad 11
[ răd ]

n.

A unit of energy absorbed from ionizing radiation, equal to 100 ergs per gram or 0.01 joule per kilogram of irradiated material.

Medical definitions for rad (2 of 2)

rad 22

abbr.

radian
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for rad

rad
[ răd ]

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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Cultural definitions for rad

rad

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

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.