The quality or state of being incompetent; lack of physical, intellectual, or moral ability; lack of qualifications or training (for a particular task); insufficiency; inadequacy; as, the incompetency of a child for hard labor, or of an idiot for intellectual efforts.

Lack of competency or legal fitness; incapacity; disqualification, as of a person to be heard as a witness, or to act as a juror, or of a judge to try a cause.

Competency is a legal concept that refers both to a person's right and ability to manage his/her own affairs and make life decisions. A competent person is entitled to make decisions; an incompetent person has a legal representative, or "guardian," who makes decisions on behalf of the person determined to be incompetent. Adults are presumed competent while minors are presumed incompetent. The presumed incompetence of a minor can be overcome by "emancipation" or can be modified by laws pertaining to certain proceedings. The presumed competence of an adult can be overcome by special judicial proceedings to declare the person incompetent, proceedings for "interdiction", or for a "continuing tutorship". Without clear proof, adults are considered competent and able to make their own decisions.

See incompetance.