vt, chal*lenged  chal*leng*ing  :  to administer a physiological and esp. an immunologic challenge to (an organism or cell)
n :  the process of provoking or testing physiological activity by exposure to a specific substance : esp  :  a test of immunity by exposure to an antigen after immunization against it .
 
 
 
Published under license with Merriam-Webster, Incorporated.  © 1997-2024.