You would think I'd have been able to rattle off a good definition of this months before now. I never had a handle on it til now though.
NURSING - the protection, promotion, and optimization of health and abilities, prevention of illness and injury, alleviation of illness and suffering through the diagnosis and treatment of human response, and advocacy in the care of individuals, families, communities and populations.
That's the official policy statement of the American Nursing Association. It really comes down to this, medicine focuses on diagnosis and treatment of a health problem. Nursing focuses on diagnosis and treatment of the response to that health problem.