I’m not a physician - my daughter is. But you want MY definition of addiction? Mine is probably not an accepted one, but OK here it is: Addiction is the taking of chemical substances for recreation that has proceeded to the point where the person taking them is either psychologically or physically dependent on the substance to maintain their wellbeing.
That’s actually the correct definition. Addiction is using a medication or substance for other than its intended purpose to achieve a desired or pleasurable effect. So you are correct. Using something for what it is not meant for. In the case of pain giving narcotics cannot lead to addiction as the receptors for pain relief are present. If you are in pain and get a narcotic then you don’t get the euphoria of taking opioids when not in pain. So it is almost impossible to addict someone in true pain. What often confuses people is that occasionally one can become tolerant and require increasing doses. My job as an anesthesiologist is tomorovode safe and effidroce pain relief at the minimal dose possible. It takes a lot of time and understanding of the patients unique needs.