1. State of complete physical, mental and social well-being, and not merely the absence of disease or infirmity.

2. State of dynamic balance in which an individual's or a group's capacity to cope with the circumstances of living is at an optimal level.

3. State characterised by anatomical, physiological and psychological integrity, ability to perform personally valued family, work and community roles; ability to deal with physical, biological, psychological and social stress; a feeling of wellbeing; and freedom from the risk of disease and untimely death.

4. In ecology, a sustainable steady state in which humans and other living organisms can coexist indefinitely.