in‧com‧pe‧tence /ɪnˈkɒmpɪtəns/
Pronunciation[in-kom-pi-tuhns]
–noun
1. the quality or condition of being incompetent; lack of ability.
Also, in‧com‧pe‧ten‧cy.
http://dictionary.reference.com/search?r=2&q=incompetency
then ,
in‧com‧pe‧tent /ɪnˈkɒmpɪtənt/
Pronunciation[in-kom-pi-tuhnt]
–adjective
1. not competent; lacking qualification or ability; incapable: an incompetent candidate.
2. characterized by or showing incompetence: His incompetent acting ruined the play.
3. Law.
a. being unable or legally unqualified to perform specified acts or to be held legally responsible for such acts.
b. inadmissible, as evidence.
–noun
4. an incompetent person; a mentally deficient person.
5. Law. a person lacking power to act with legal effectiveness.
I think I'll go with #4 !