noun

• A confrontation; a dare.
  "Argentine midfielder Jonas Gutierrez added a superb second when he surged past four challenges to fire in low."
• (law) A procedure or action.
• (law) A procedure or action.
  "Consanguinity in direct line is a challenge for a judge when he or she is sitting cases."
• (law) A procedure or action.
  "We're still waiting to hear how the court rules on our challenge of the arbitrator based on conflict of interest."

verb

• (transitive) To invite (someone) to take part in a competition.
  "We challenged the boys next door to a game of football."
• (transitive) To dare (someone).
  "[...] For I challenge any Man to make any pretence to Power by Right of Fatherhood, either intelligible or poſſible in any one, otherwiſe, then either as Adams heir, or as Progenitor over his own deſcendants, naturally ſprung from him."
• (transitive) To dispute (something); to contest.
  "to challenge the accuracy of a statement or of a quotation"
• (law, transitive) To make a formal objection to a juror.