rad

¹ American  

[rad] / ræd /

noun

Physics.

1. 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.

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rad ² American  

[rad] / ræd /

noun

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

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adjective

radder, raddest

1. Slang. excellent; wonderful; cool.

   a high speed, high energy, totally rad racing game.

rad ³ American  

[rad] / ræd /

abbreviation

Mathematics.

1. radian; radians.

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rad. ⁴ American  

abbreviation

Mathematics.

1. radical.

2. radix.

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rad ¹ British  

/ ræd /

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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rad ² British  

symbol

1. radian

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rad. ³ British  

abbreviation

1. radical

2. radius

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rad Scientific  

/ 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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rad Cultural  

1. An acronym for r adiation a bsorbed d ose. A unit of energy absorbed from ionizing radiation.

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Etymology

Origin of rad¹

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

Origin of rad²

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

Origin of rad³

First recorded in 1910–15; shortening

Example Sentences

Here are three potential itineraries for three different kinds of rad dads: those who love the great outdoors, fall head over heels for food and dig the arts.

From Seattle Times • Jun. 1, 2024

Also: How Liquid Death made water rad as hell, and the uncertain fate of TikTok in America.

From Slate • Mar. 16, 2024

“It’s been pretty rad being able to go up and snowboard in the morning, go out and fish in the afternoon, then go stare at waterfalls for the sunset,” he said.

From Los Angeles Times • Jul. 22, 2023

I feel like I never imagined a year in my career where I would get to work more than I am not working, and that's happening, and that's pretty rad.

From Salon • Jun. 4, 2023

“You’ve been here a fraction of the time everyone else has, but you’ve gotten pretty much double the amount of litter off the streets. Pretty rad, Fern.”

From "The Wrong Way Home" by Kate O’Shaughnessy

Related Words

• astonishing
• astounding
• awesome
• breathtaking
• fantastic
• incredible
• marvelous
• outrageous
• phenomenal
• remarkable
• spectacular
• superb
• terrific
• unbelievable