Incompetence (noun)

1. A lack of ability, skill or qualifications to perform a task.
2. Inefficiency or inability to carry out a job or task correctly.
3. An inability to make good or appropriate decisions.

Origin:

Derived from the latin word 'incompetentia' meaning 'not suitable' or 'not capable'.

Examples:

1. His incompetence as a manager led to the downfall of the company.
2. She was fired from her job due to her incompetence in handling the clients.
3. The pilot's incompetence caused the plane crash.
4. The incompetence of the politicians was evident in their inability to solve the problem.
5. Their incompetence in dealing with the situation was the reason for the delay.