something that needs great mental or physical effort in order to be done successfully and therefore tests a person's ability
Finding a solution to this problem is one of the greatest challenges faced by scientists today.
You know me - I like a challenge.
The crossword puzzle posed a significant challenge for even the most experienced puzzlers.
Overcoming the obstacle course was a physical and mental challenge for the participants.
The new job presented a fresh set of challenges, requiring adaptability and problem-solving skills.
The scientific experiment was designed to address a specific research challenge in the field.
