counterchallenge
1. [ verb ] challenge in turn
Examples:

"The authentication was counterchallenged"

Related terms: challenge
Similar spelling:   countercharge
  counterchange
  countervailing
  counterbalance
  counterbalanced
  counter_check
  counteroffensive
  counterbalancing
  counterfactual
  counterexample
  countercurrent
  counterculture
  counterintelligence
  counterargument
  counterproposal