variants: or radio-

Definition of radi- 

1 : radiant energy : radiation radioactive radiopaque

2 : radioactive radioelement

3 : radium : X-rays radiotherapy

4 : radioactive isotopes especially as produced artificially radiocarbon

5 : radio radiotelegraphy

6 : radius bone radio-ulna

History and Etymology for radi-

French, from Latin radius ray

Keep scrolling for more

Learn More about radi-

Dictionary Entries near radi-

rade

raden

Radetzky

radi-

radiac

radial

radial arm

Statistics for radi-

Look-up Popularity

Comments on radi-

What made you want to look up radi-? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

evasion of direct action or statement

Get Word of the Day daily email!

Test Your Vocabulary

Great Scrabble Words—A Quiz

  • scrabble-tiles-that-read-scrabble-quiz
  • Which of the following Q-without-U words means the number five in cards or dice?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Citation

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!