This chapter examines different definitions of stress and introduces the author's new definition. It discusses how stress has been defined through: 1) early physiological research on stress responses, 2) psychological research on stress as a stimulus or transaction between person and environment, and 3) the holistic health movement's perspective of stress affecting multiple dimensions of wellness. The author's definition integrates these views by defining stress as a holistic transaction between an individual and potential stressor, resulting in a stress response, influenced by the person's overall well-being across emotional, spiritual, environmental, physical, social, and intellectual dimensions.