1. the inability to carry out a required task or activity adequately.

2. in law, the inability of a defendant to participate meaningfully in criminal proceedings, which include all elements of the criminal justice system, from initial interrogation to sentencing. Defendants who do not have the ability to communicate with attorneys or understand the proceedings may be ruled incompetent to stand trial (see competency to stand trial). See also Dusky standard.

3. in law, the inability to make sound judgments regarding one’s transactions or personal affairs. See legal capacity. Also called incompetency. Compare competence. —incompetent adj.