Top Definitions
Quiz
Related Content
Examples
British
Scientific
Cultural

rad

¹

[ rad ]

/ ræd /

Save This Word!

See synonyms for rad on Thesaurus.com

noun Physics.

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

VIDEO FOR RAD

Do You Remember This Radical 80s Slang?

When you re-hear to this 80's slang you'll feel like you've been transported back in time. Do you remember these totally 80's words?

MORE VIDEOS FROM DICTIONARY.COM

QUIZ

CAN YOU ANSWER THESE COMMON GRAMMAR DEBATES?

There are grammar debates that never die; and the ones highlighted in the questions in this quiz are sure to rile everyone up once again. Do you know how to answer the questions that cause some of the greatest grammar debates?

Question 1 of 7

Which sentence is correct?

His boss, whom he admires, is waiting to meet with him about the big project.

His boss, who he admires, is waiting to meet with him about the big project.

TAKE THE QUIZ TO FIND OUT

Origin of rad

¹

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

Words nearby rad

racoon, RACQ, racquet, racquetball, racy, rad, RADA, radar, radar astronomy, radar beacon, radar gun

Other definitions 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

Other definitions for rad (3 of 4)

rad³

[ rad ]

/ ræd /

abbreviation Mathematics.

radian; radians.

Origin of rad

³

First recorded in 1910–15; shortening

Other definitions for rad (4 of 4)

rad.

abbreviation Mathematics.

radical.

radix.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use rad in a sentence

He had spent about two minutes exposed to a radiation field he estimated at 2,000 rads per hour, enough to make a person ill.
The US military’s first experiment with portable nuclear reactors was short and tragic|Purbita Saha|July 22, 2021|Popular-Science
When I put them on my feet, it’s time to go do something rad.
The Outdoor Inspirations of Thomas Rhett’s New Album|smurguia|July 12, 2021|Outside Online
I believe that if we start honoring mental health like we honor getting rad in the mountains, lives will be saved.
We Need to Talk About Mental Health in the Mountains|Drew Petersen|June 30, 2021|Outside Online
Gardening is far less “rad” than running 50 miles or climbing sandstone, after all.
Your Mellow Outdoor Activities Are Rad, Too|Blair Braverman|June 1, 2021|Outside Online

I wouldn’t say I’m a rad skier now, but I can ski at moderate speed and feel confident and not like I’m a hazard to myself or to others.
A Brief Excursion into Skiing's Cyborg Future|Nick Heil|December 16, 2020|Outside Online
Jim really paved the way—on film and in television—for people to see young, rad chicks kick ass and take names.
Jessica Alba on 'Sin City,' Typecasting, and How Homophobia Pushed Her Away From the Church|Marlow Stern|August 18, 2014|DAILY BEAST
If Hugh Jackman is totally heterosexual, his mode is a confusing—and not in a good, rad way—butch-camp.
Hugh Jackman's Tony Jumping Fail, Plus the Winners and Standout Moments of Broadway's Biggest Night|Tim Teeman|June 9, 2014|DAILY BEAST
Nashville: Broadman Holman Publishers, 1996 Rad, Gerhard von.
The Backstory of ‘Noah’ Is Full of Giants, Horny Angels, and a Grieving God|Tim Townsend|March 28, 2014|DAILY BEAST
In October 2007, Hourani launched his first ready-to-wear unisex line, RAD by Rad Hourani, at a small art gallery in Paris.
Rad Hourani, The First Unisex Couture Designer|Erin Cunningham|January 29, 2014|DAILY BEAST
The ‘Today’ Show Horses Around Who knew David Gregory was such a rad dancer?
Ai Weiwei, Ban Ki-moon, Ponies & More Best ‘Gangnam Style’ Parodies (VIDEO)|Melissa Leon, Kevin Fallon|October 26, 2012|DAILY BEAST
Since ginger is not stated to be one of the ingredients of the compound, it, perhaps, may be the mysterious stranger latalia rad.
The Propaganda for Reform in Proprietary Medicines, Vol. 1 of 2|Various
Professor Day reports that he was unable to find any mention of the drug of latalia rad.
The Propaganda for Reform in Proprietary Medicines, Vol. 1 of 2|Various
This would seem to indicate that what has already been intimated by The Journal—namely, that latalia rad.
The Propaganda for Reform in Proprietary Medicines, Vol. 1 of 2|Various
This seems very open and above board, except as to quantities, until one tries to find out what latalia rad.
The Propaganda for Reform in Proprietary Medicines, Vol. 1 of 2|Various
Experts to whom this remedy was submitted were unable even to find mention of such a drug or plant as latalia rad.
The Propaganda for Reform in Proprietary Medicines, Vol. 1 of 2|Various

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

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.