1. a psychological demarcation that protects the integrity of an individual or group or that helps the person or group set realistic limits on participation in a relationship or activity.

2. in psychotherapy, an important limit that is usually set by the therapist as part of the ground rules in treatment. Boundaries may involve areas of discussion (e.g., the therapist’s personal life is off limits) or physical limits (e.g., rules about touching), which are guided by ethical codes and standards. Respect for boundaries by both the therapist and client is an important concept in the therapeutic relationship.