Incompetent (adjective)

1. Not having the necessary abilities, knowledge, or qualifications for a particular task or role.
2. Not able to perform a task or role in an effective or efficient way.
3. Not able to function in an acceptable or satisfactory way.

Origin:

From latin incompetentem, from in- ("not") + competentem ("competen.t")

Examples:

1. The employee was found to be incompetent.
2. The doctor was incompetent in performing the surgery.
3. The teacher was deemed incompetent by the school board.
4. The government was criticized for being incompetent.
5. The lawyer was incompetent in presenting the case.