noun

 

difficult something that is difficult and that tests someone's ability or determination

Finding a decision that pleases everyone is the challenge which now faces the committee.

 

invitation an invitation to compete in a game or a fight

I'm sure Paul will race you. He never refuses a challenge.

 

disagreement an expression of disagreement with ideas, rules, or someone's authority

a challenge to the authority of the President

 

verb

 

disagree to express disagreement with ideas, rules, or someone's authority

The election results are being challenged.

 

invite to invite someone to compete in a game or fight

He challenged Smith to a fight.