1. A unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material
   "The safety officer monitored radiation levels in rads"
    
2. The unit of plane angle adopted under the Système International d'Unités; equal to the angle at the centre of a circle subtended by an arc equal in length to the radius (approximately 57.295 degrees)
   "Mathematicians prefer to use rads rather than degrees in many calculations";
   - radian
    
3. [informal] A person who has radical ideas or opinions
   "The young rad advocated for complete system change";
   - radical

1. Of the highest quality, skill, etc.; very good or impressive
   "a rad reporter";
   - ace [informal], A-one [informal], crack [informal], first-rate, super, tiptop, topnotch [informal], top-notch [informal], tops [informal], A1 [informal], top-class, gnarly [N. Amer, informal], excellent, first-class, fantabulous [informal], splendid, ripping [Brit, archaic, informal], mean [informal], outstanding, lush [Brit, informal], brilliant, beezer [UK, archaic], stellar [informal], awesome [informal], top-drawer, dope [N. Amer, informal], socko [N. Amer, informal], righteous [US, slang], fab [Brit, informal], crucial [slang], radical [N. Amer, slang], nang [Brit, slang], phat [slang], legit [US, slang], awesomesauce [informal], amazeballs [informal], beaut [Austral, NZ, informal], lit [US, slang], storming [Brit, informal], blinding [Brit, slang], stonking [Brit, informal], brill [Brit, informal], wicked [slang], cushty [Brit, informal], def [slang], magic [Brit, slang], smokin' [slang], smoking [slang], sick [N. Amer, slang]

Derived forms: rads

See also: super-duper [informal], superior

Type of: actor, angular unit, doer, radioactivity unit, worker

Encyclopedia: Rad