Challenge (noun)

1. A demand for someone to prove or justify something.
2. A task or situation that tests a person's ability or resources.

Origin:

Late middle english: from old french chalenge, from latin calumnia "accusation, false charge", from calvi "to call, charge".

Examples:

1. The job was a challenge for her, but she rose to it.
2. They took on the challenge of climbing the mountain.
3. The challenge for the company is to increase sales.
4. The challenge was to complete the puzzle in under an hour.
5. The new project is a big challenge for the team.