1. a difficult task or situation that tests one's abilities
2. an invitation to compete or fight
3. a questioning of the truth or validity of something

1. to invite someone to compete or fight
2. to question or dispute the truth or validity of something
3. to test the abilities of someone or something

Examples

• Learning a new language is a real challenge.
• The mountain climb presented many challenges.
• He issued a challenge to a chess match.
• The lawyer challenged the witness's testimony.
• She challenged him to prove his claim.
• The difficult course will challenge even advanced students.
• They decided to challenge the court's decision.
• This puzzle really challenges your problem-solving skills.