rad

¹

[ rad ]

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.

rad

²

[ rad ]

noun

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

adjective

, rad·der, rad·dest.

1. Slang. excellent; wonderful; cool:

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

rad

³

[ rad ]

abbreviation for

, Mathematics.

1. radian; radians.

rad.

⁴

abbreviation for

, Mathematics.

1. radical.
2. radix.

rad

¹

/ 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

rad

²

symbol for

1. radian

rad.

³

abbreviation for

1. radical
2. radius

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.

rad

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

Word History and Origins

Origin of rad¹

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

Origin of rad²

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

Origin of rad³

First recorded in 1910–15; shortening

Word History and Origins

Origin of rad¹

C20: shortened from radiation

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

He says “rad” without irony and gets away with it.

From Los Angeles Times

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

From Los Angeles Times

“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

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

Related Words

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