²challenge

noun

Medical Definition of CHALLENGE

: the process of provoking or testing physiological activity by exposure to a specific substance; especially : a test of immunity by exposure to an antigen after immunization against it

Learn More About

Dictionary: Definition of "challenge"

Thesaurus: All synonyms and antonyms for "challenge"

Spanish Central: Spanish translation of "challenge"

Nglish: Translation of "challenge" for Spanish speakers

Britannica English: Translation of "challenge" for Arabic speakers

Browse

Seen & Heard

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

View Seen & Heard Highlights from Around the Site

Test Your Vocabulary!

10 Charming Words for Nasty People

Put-downs with flair

Learn More

When "Literally" isn't, well, literal

How to use a word that (literally) drives some people nuts.

Watch Now

Know what this is?

Test your vocab with our fun, fast game

Go Play

Fear of cats?

Ailurophobia, and 9 other unusual fears