incompetent

/ɪnˈkɑmpɪtənt/
adjective
  1. Not having the necessary skill, knowledge, or ability to do something successfully.
    • She felt incompetent when she couldn't answer the simple math question.
    • The court ruled that the doctor was incompetent and should lose his license.
    • The incompetent plumber left the pipes leaking even worse than before.
noun
  1. A person who lacks the necessary skill or ability to do a job or task.
    • The team was full of incompetents who couldn't meet a single deadline.
    • The manager hired a series of incompetents before finally finding a good worker.
    • He was dismissed as a hopeless incompetent after losing the client's account.