COPD: Terms to Know Addiction. A compulsive need to use a substance such as tobacco, drugs, or alcohol. Addiction can be physical or psychological. In physical addiction, your body becomes dependent on a substance and goes through withdrawal symptoms, such as diarrhea and shaking, if the substance is stopped. In psychological addiction, you have a strong craving for the substance. Your brain chemistry may have changed so that you believe that you need the substance to survive. Chest X-ray. A diagnostic ...