1. the ability of a person to perform independently the various tasks required in daily life, a core concept in rehabilitation. See activities of daily living; instrumental activities of daily living.

2. as defined in 1973 by Gordon W. Allport, a general principle of motivation stating that during the performance of purposeful, goal-oriented behavior, various derivative drives emerge as independent units from the original drive that inspired the behavior. For example, studying motivated by the desire to obtain high grades may be gradually replaced by the desire for (and therefore pursuit of) knowledge for its own sake.