Evidence-based healthcare (Evidence-based Medicine; Evidence-based Nursing; etc.) has many definitions. A widely cited definition is adapted from this definition of evidence-based medicine (EBM):
The conscientious, explicit, and judicious use of current best evidence in making decisions about the care of individual patients. The practice of evidence-based medicine means integrating individual clinical expertise with the best available external clinical evidence from systematic research. (Sackett et al., 1996, p. 71)
It is a problem-solving approach to the delivery of health care that integrates the best evidence from research and patient care data with clinician expertise and patient preferences and values. When delivered in a context of caring and in a supportive organizational culture, the highest quality of care and best patient outcomes can be achieved.
References
Sackett, D., Rosenberg, W., Gray, J., Haynes, R., & Richardson, W. (1996). Evidence-based medicine: What it is and what it isn't. British Medical Journal, 312(7023), 71-72. https://doi.org/10.1136/bmj.312.7023.71