Hence, oncologist definition would be a medical professional dedicated to the study, diagnosis, and treatment of cancerous conditions. Understanding oncology meaning in everyday terms Oncology meaning can be summed up as the branch of medicine that deals with the prevention, diagnosis, and treatment of cancer. What does oncology mean? Oncology is the study of cancer. The word comes from the Greek word onkos, meaning tumor or mass. It is the branch of medicine that focuses on the diagnosis, treatment, and care of people with cancer. An oncologist is a doctor who diagnoses and treats cancer and blood disorders. Learn about the different types of oncologists, their education and training, and what to prepare for your first visit. The term oncologist meaning refers to a doctor who specializes in diagnosing, treating, and managing cancer. These medical professionals undergo extensive training to provide the best oncology care for patients.