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  

abbreviation

1. radical

2. radius

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rad ³ British  

symbol

1. radian

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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

“We believe in respect, kindness, and love. We are huge fans of other women-owned companies, LGBTQIA+ communities, and rad men’s companies too. None of that feels political to us,” she said.

From Slate • Jul. 23, 2024

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

She even got down and did some pretty rad splits on this long-forgotten sad carpet.

From Los Angeles Times • Dec. 20, 2023

Madisynn drops into our lives by way of a "diff dimensh" otherwise known as a hellscape, which she navigates like any other rad party, or her hometown of Fort Lauderdale.

From Salon • Dec. 26, 2022

I’m not going to hop in unless there’s something really rad.

From "Free Lunch" by Rex Ogle

Related Words

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