A definitive diagnosis refers to a medical opinion or conclusion that is based on thorough examination and evaluation of a patient's symptoms, medical history, and any other relevant factors. It represents an accurate identification of a particular disease or condition, often following extensive testing and analysis by healthcare professionals. The term "definitive" implies that the diagnosis provides a clear answer to the patient's symptoms and is not subject to change based on additional information. In summary, a definitive diagnosis offers certainty about what medical issue a person may be experiencing, which can help guide appropriate treatment and management options.