1. Study of behavior and of the functions and processes of the mind, especially as related to the social and physical environment. 2. Profession (clinical psychologist) that involves the practical applications of knowledge, skills, and techniques in the understanding of, prevention of, or solutions to individual or social problems, especially in regard to the interaction between the individual and the physical and social environment. 3. Mental, motivational, and behavioral characteristics and attitudes of an individual or group of individuals.