competence

1. General: (plural competences) cluster of related abilities, commitments, knowledge, and skills that enable a person (or an organization) to act effectively in a job or situation. In comparison to 'competency' (plural competencies) which refers to a cluster of abilities relating to excellence in a specific activity, competence indicates sufficiency (state of being 'good enough') of knowledge and skills that enable one to act in a wide variety of situations. Because each level of responsibility has its own requirements, competence can occur in any period of a person's life or at any stage of his or her career.

2. Legal: Capacity of a person to understand a situation and to act reasonably. Disputes regarding the competence of an individual are settled by a judge and not by a professional (such as a doctor or a psychiatrist) although the judge may seek expert opinion before delivering at a judgment. Also called legal capacity.

The most important thing in terms of your circle of competence is not how large the area of it is, but how well you've defined the perimeter.