Physiological opioid dependence: An adaptive physiological state arising from repeated use of opioids where the body requires particular dose and pattern of opioid use to maintain physiological and functional stability. A person dependent on opioids can often (but not always) experience acute opioid withdrawal symptoms and protracted withdrawal syndrome. This should not be equated with opioid addiction, opioid use disorder or ICD-10 diagnosis of Opioid Dependence.