Table 1. Definitions of Opioid Use Disorders.

Concept	Definition
Substance use disorder	A group of intellectual, behavioral and physical symptoms that imply a patient has continued using a substance despite substantial substance-related complications. The diagnosis is based on a compulsive pattern of behaviors that can be attributed to the use of the substance.
Tolerance	A condition of adaptation described as distinct increases in dosage of a drug required to accomplish desired effect. May also be diagnosed in patients in whom repeat dosing results in lessening of one or more opioid effects over time.
Physical Dependence	A condition of adaptation demonstrated by patients who experience withdrawal syndromes elicited by abrupt cessation, dose reduction, lowered blood concentration of the drug, and/or administration of an antagonist.
Addiction	A chronic, neurobiologic disease with psychosocial, genetic, and environmental variables prompting its development. Addicted patients exemplify one or more of the following: failure to control drug use, habitual use, use without regard to the harm it causes, and craving. This term is considered outdated.
Aberrant drug-related behavior	A behavior that does not agree with the treatment plan made between a patient and his or her doctor.
Misuse	Use of a medication for nonmedical use, or for reasons other than prescribed. Misuse can be intentional or unintentional use of an opioid or other drug in a way inconsistent with medical guidelines or the law, including changes made to drug doses or the sharing of medications.
Abuse	Misuse with prominent consequences. Often defined as substance use with the purpose to adapt or control attitude or state of mind in a way that is not legal or damaging to oneself or others.
Diversion	The purposeful exchange of a controlled substance from legal distribution and dispensing channels into illegal channels.
Withdrawal	A health condition occurring when the concentration of a substance in the blood or tissue are lowered in patients who had previously maintained high concentrations as a result of extended and exorbitant use. The conditions described vary between drug classes and patient to patient.