Merriam-Webster Logo
SINCE 1828
dictionary
thesaurus
view recents

radi-

combining form
Save Word
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-

Statistics for radi-

Cite this Entry

“Radi-.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/radi-. Accessed 18 Apr. 2021.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

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).

Show Comments  Hide Comments 

WORD OF THE DAY

forfend

Listen to the pronunciation of forfend

See Definitions and Examples »

Test Your Vocabulary

The Exceptions Quiz III

  • one green toy robot amidst many red toy robots
  • Which of these words does not mean "nonsense"?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Typeshift

Anagram puzzles meet word search.

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!

Words at Play
Ask the Editors
Word Games