rad

noun

A non-SI unit of absorbed dose of radiation, equal to 0.01 gray.

noun

In the International System of Units, the derived unit of plane angular measure of angle equal to the angle subtended at the centre of a circle by an arc of its circumference equal in length to the radius of the circle. Symbol: rad

1. Anything which radiates or emits rays.
2. A device that lowers engine coolant temperature by conducting heat to the air, through metal fins.
3. (of buildings) A finned metal fixture that carries hot water or steam in order to heat a room.
4. A type of antenna.

1. Favoring fundamental change, or change at the root cause of a matter.

   His beliefs are radical.

2. Pertaining to a root (of a plant).
3. Pertaining to the basic or intrinsic nature of something.
4. Thoroughgoing; far-reaching.

   The spread of the cancer required radical surgery, and the entire organ was removed.

5. Of or pertaining to the root of a word.
6. (of a sound) Produced using the root of the tongue.
7. Involving free radicals.
8. Relating to a radix or mathematical root.

   a radical quantity; a radical sign

9. (1980s & 1990s) Excellent; awesome.

   That was a radical jump!

noun

The distance between the front and rear sights of a firearm.