Abuse:
Self-administration of any drug in a culturally disapproved manner that causes adverse consequences.

Addiction:
A behavioral pattern of drug abuse characterized by overwhelming involvement with the use of a drug (compulsive use), the securing of its supply and a high tendency to relapse after discontinuation.

Dependence:
The physiological state of neuroadaptation produced by repeated administration of a drug, necessitating continued administration to prevent the appearance of the withdrawal syndrome.

Rebound:
The exaggerated expression of the original condition sometimes experienced by patients immediately after cessation of an effective treatment.

Relapse:
The reoccurrence on discontinuation of an effective medical treatment of the original condition from which the patient suffered.

Tolerance:
Tolerance has developed when after repeated administration, a given dose of a drug produces decreased effect, or conversely, when increasingly larger doses must be administered to obtain the effects observed with the original use.

Withdrawal:
The psychologic and physiologic reactions to abrupt cessation of a dependence-producing drug.