Addiction  Glossary

Common terms and phrases in the world of addictions.

Irecover addiction treatment centers

Commonly Used Terms in Addiction Science


Abstinence: Not using drugs or alcohol.

Addiction: A chronic, relapsing disorder characterized by compulsive (or difficult to control) drug seeking and use despite harmful consequences, as well as long-lasting changes in the brain. In the past, people who used drugs were called “addicts.” Current appropriate terms are people who use drugs and drug users.

Agonist: A chemical substance that binds to and activates certain receptors on cells, causing a biological response. Oxycodone, morphine, heroin, fentanyl, methadone, and endorphins are all examples of opioid receptor agonists.

Amphetamine: A stimulant drug that acts on the central nervous system (CNS). Amphetamines are medications prescribed to treat attention deficit hyperactivity disorder (such as Adderall®) and narcolepsy.

Anabolic-androgenic steroids: Synthetic substances similar to the male hormone testosterone. Often known as “anabolic steroids.” They can promote muscle growth (anabolic effects) and produce changes in male sexual characteristics (androgenic effects) in both males and females.

Analgesics: A group of medications that reduce pain.

Anesthetic: A drug that causes insensitivity to pain and is used for surgeries and other medical procedures.

Antagonist: A chemical substance that binds to and blocks the activation of certain receptors on cells, preventing a biological response. Naloxone is an example of an opioid receptor antagonist.


Barbiturate: A type of CNS depressant sometimes prescribed to promote relaxation and sleep, but more commonly used in surgical procedures and to treat seizure disorders.

Basal ganglia: The area of the brain that plays an important role in positive forms of motivation, including the pleasurable effects of healthy activities like eating, socializing, and sex, and are also involved in the formation of habits and routines. These areas form a key node of what is sometimes called the brain’s “reward circuit.”

Benzodiazepine: A type of CNS depressant sometimes prescribed to relieve anxiety, panic, or acute stress reactions. Some benzodiazepines are prescribed short-term to promote sleep. Diazepam (Valium®) and alprazolam (Xanax®) are among the most widely prescribed benzodiazepine medications.

Brainstem: A group of brain structures that process sensory information and control basic functions needed for survival such as breathing, heart rate, blood pressure, and arousal.

Buprenorphine: An opioid partial agonist medication prescribed for the treatment of opioid addiction that relieves drug cravings without producing the high or dangerous side effects of other opioids.


Cannabidiol (CBD): A component of the marijuana plant without mind-altering effects that is being studied for possible medical uses.

Cannabinoid receptor: The receptor in the brain that recognizes and binds cannabinoids that are produced in the brain (anandamide) or outside the body (THC).

Cannabinoids: Chemicals that bind to cannabinoid receptors in the brain. They are found naturally in the brain (anandamide, 2-arachidonoylglycerol) and also in marijuana (THC and CBD). They are involved in a variety of mental and physical processes, including memory, thinking, concentration, movement, pain regulation, food intake, and reward.

Cannabis: Another name for the marijuana plant, Cannabis sativa.

Cardiovascular system: The system consisting of the heart and blood vessels. It delivers nutrients and oxygen to all cells in the body.

Central nervous system (CNS): The system consisting of the nerves in the brain and spinal cord.

Cerebellum: A part of the brain that helps regulate posture, balance, and coordination. It is also involved in the processes of emotion, motivation, memory, and thought.

Cerebral cortex: The gray matter that covers the surface of the cerebral hemispheres, whose functions include sensory processing and motor control along with language, reasoning, decision-making, and judgment.

Cerebral hemispheres: The right and left halves of the brain.

Cerebrum: The upper part of the brain consisting of the left and right hemispheres.

CNS depressants: A class of drugs that include sedatives, tranquilizers, and hypnotics. These drugs slow brain activity, making them useful for treating anxiety, panic, acute stress reactions, and sleep disorders.

Cognition (n): Of or relating to the act or process of thinking, understanding, learning, and remembering.

Cognitive-behavioural therapy (CBT): A form of psychotherapy that teaches people strategies to identify and correct problematic associations among thoughts, emotions, and behaviours in order to enhance self-control, stop drug use, and address a range of other problems that often co-occur with them.

Comorbidity: When two disorders or illnesses occur in the same person. Drug addiction and other mental illnesses or viral infections (HIV, hepatitis) are often comorbid. Also referred to as co-occurring disorders.

Contingency management: A treatment approach based on providing incentives to support positive behaviour change.

Craving: A powerful, often overwhelming desire to use drugs.


Dependence: A condition that can occur with the regular use of illicit or some prescription drugs, even if taken as prescribed. Dependence is characterized by withdrawal symptoms when drug use is stopped. A person can be dependent on a substance without being addicted, but dependence sometimes leads to addiction.

Detoxification: A process in which the body rids itself of a drug, or its metabolites. Medically-assisted detoxification may be needed to help manage a person’s withdrawal symptoms. Detoxification alone is not a treatment for substance use disorders, but this is often the first step in a drug treatment program.

Dopamine: A brain chemical, classified as a neurotransmitter, found in regions of the brain that regulate movement, emotion, motivation, and reinforcement of rewarding behaviour. Dopamine release in reward areas of the brain is caused by all drugs to which people can become addicted.

Drug abuse: An older diagnostic term that defined use that is unsafe, use that leads a person to fail to fulfill responsibilities or gets them in legal trouble, or use that continues despite causing persistent interpersonal problems. This term is increasingly avoided by professionals because it can perpetuate stigma. Current appropriate terms include: drug use (in the case of illicit substances), drug misuse (in the case of problematic use of legal drugs or prescription medications) and addiction (in the case of substance use disorder).

Drugged driving: Driving a vehicle while impaired due to the intoxicating effects of recent drug use.


Electronic cigarette: A battery-operated device that people use to inhale an aerosol, which typically contains nicotine, flavourings, and other chemicals; also called e-cigarette, e-cigs, e-vaporizers, or electronic nicotine delivery system.


Flashback: A sudden but temporary recurrence of aspects of a drug experience (including sights, sounds, and feelings) that may occur days, weeks, or even more than a year after using drugs that cause hallucinations.


Hallucinations: Sensations, sounds and/or images that seem real though they are not.

Hippocampus: An area of the brain crucial for learning and memory.

Hypothalamus: A part of the brain that controls many bodily functions, including eating, drinking, body temperature regulation, and the release of many hormones.


Illicit: Illegal or forbidden by law.

Impulsivity: A tendency to act without foresight or regard for consequences and to prioritize immediate rewards over long-term goals.

Injection drug use (IDU): The act of administering drugs by injection. Blood-borne viruses, like HIV and hepatitis, can be transmitted via shared needles or other drug injection equipment.

Intranasal: Taken through the nose.


Limbic system: Interconnected brain structures that process feelings, emotions, and motivations. It is also important for learning and memory.


Mental disorder: A mental condition marked primarily by disorganization of personality, mind, and emotions that seriously impairs the psychological or behavioural functioning of the individual. This is sometimes referred to as a mental health condition. Addiction is a mental disorder.

Methadone: A long-acting opioid agonist medication used for the treatment of opioid addiction and pain. Methadone used for opioid addiction can only be dispensed by opioid treatment programs certified by SAMHSA and approved by the designated state authority.

Motivational Enhancement Therapy: A counselling approach that uses motivational interviewing techniques to help individuals resolve any uncertainties they have about stopping their substance use. The therapy helps the person strengthen their own plan for change and engagement in treatment.


Naloxone: An opioid antagonist medication approved by the FDA to reverse an opioid overdose. It displaces opioid drugs (such as morphine or heroin) from their receptor and prevents further opioid receptor activation.

Naltrexone: A long-acting opioid antagonist medication that prevents receptors from being activated by other opioids. Naltrexone is used to treat alcohol and opioid use disorders.

Neonatal abstinence syndrome (NAS): A condition of withdrawal that occurs when certain drugs pass from the mother through the placenta into the fetus’ bloodstream during pregnancy causing the baby to become drug dependent and experience withdrawal after birth. The type and severity of a baby’s withdrawal symptoms depend on the drug(s) used, how long and how often the mother used, how her body broke down the drug, and if the baby was born full term or prematurely. NAS can require hospitalization and treatment with medication to relieve symptoms.

Neurobiology: The study of the anatomy, function, and diseases of the brain and nervous system.

Neuron (nerve cell): A unique type of cell found in the brain and throughout the body that specializes in the transmission and processing of information.

Neurotransmitter: A chemical compound that acts as a messenger to carry signals from one nerve cell to another.

Norepinephrine: A neurotransmitter that affects heart rate, blood pressure, stress, and attention.

Nucleus accumbens: A brain region in the ventral striatum involved in motivation and reward. Nearly all addictive drugs directly or indirectly increase dopamine in the nucleus accumbens, contributing to their addictive properties.


Opioid receptors: Proteins on the surface of neurons, or other cells, that are activated by endogenous opioids, such as endorphins, and opioid drugs, such as heroin. Opioid receptor subtypes include mu, kappa, and delta.

Overdose: An overdose occurs when a person uses enough of a drug to produce a life-threatening reaction or death.


Paranoia: Extreme and unreasonable distrust of others.

Partial agonist: A substance that binds to and activates a receptor to a lesser degree than a full agonist.

Pharmacodynamics: The way a drug acts on the body. This includes the drug’s interaction with its biological target and the resulting changes (such as activation or blocking of receptors), as well as the relationship between drug dosing and drug effects.

Pharmacokinetics: What the body does to a drug after it has been taken, including how rapidly the drug is absorbed, broken down, and processed by the body.

Pharmacotherapy: Treatment using medications.

Prefrontal cortex: The front part of the brain responsible for reasoning, planning, problem solving, and other higher cognitive functions. This area of the brain is not fully mature until adulthood, which confers greater vulnerability to drug use on the adolescent brain.

Prescription drug misuse: The use of a medication in ways or amounts other than intended by a doctor, by someone other than for whom the medication is prescribed, or for the experience or feeling the medication causes. This term is used interchangeably with “non-medical” use, a term employed by many national drug use surveys.

Psychedelic drug: A drug that distorts perception, thought, and feeling. This term is typically used to refer to drugs with hallucinogenic effects.

Psychoactive: Having a specific effect on the brain.

Psychosis: Delusional or disordered thinking detached from reality; symptoms often include hallucinations.

Psychotherapeutics: Drugs that have an effect on the function of the brain and that are often used to treat psychiatric/neurologic disorders; includes pain relievers, tranquilizers, sedatives, and stimulants.

Psychotropic: Mind-altering.


Receptor: A molecule located on the surface of a cell that recognizes specific chemicals (normally neurotransmitters, hormones, and similar endogenous substances) and transmits the chemical message into the cell.

Recovery: A process of change through which people with substance use disorders improve their health and wellness, live self-directed lives, and strive to reach their full potential.

Relapse: In drug addiction, relapse is the return to drug use after an attempt to stop. Relapse is a common occurrence in many chronic health disorders, including addiction, that requires frequent behavioural and/or pharmacologic adjustments to be treated effectively.

Remission: A medical term meaning that major disease symptoms are eliminated or diminished below a pre-determined harmful level.

Reward: Pleasurable feelings that reinforce behaviour and encourage repetition.

Reward system (or brain reward system): A brain circuit that includes the ventral tegmental area, the nucleus accumbens, and the prefrontal cortex.

Risk factors: Factors that increase the likelihood of beginning substance use, of regular and harmful use, and of other behavioural health problems associated with use.

Route of administration: The way a drug is taken into the body. Drugs are most commonly taken by eating, drinking, inhaling, injecting, snorting, or smoking.


Self-medication: The use of a substance to lessen the negative effects of stress, anxiety, or other mental disorders (or side effects of their pharmacotherapy) without the guidance of a health care provider. Self-medication may lead to addiction and other drug- or alcohol-related problems.

Serotonin: A neurotransmitter involved in a broad range of effects on perception, movement, and emotions. Serotonin and its receptors are the targets of most hallucinogens.

Stigma: A set of negative attitudes and beliefs that motivate people to fear and discriminate against other people. Many people do not understand that addiction is a disorder just like other chronic disorders. For these reasons, they frequently attach more stigma to it. Stigma, whether perceived or real, often fuels myths and misconceptions, and can influence choices. It can impact attitudes about seeking treatment, reactions from family and friends, behavioral health education and awareness, and the likelihood that someone will not seek or remain in treatment.

Substance use disorder (SUD): A medical illness caused by disordered use of a substance or substances. According to the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), SUDs are characterized by clinically significant impairments in health, social function, and impaired control over substance use and are diagnosed through assessing cognitive, behavioral, and psychological symptoms. An SUD can range from mild to severe.


THC: Delta-9-tetrahydrocannabinol; the main mind-altering ingredient in marijuana.

Tolerance: A condition in which higher doses of a drug are required to achieve the desired effect.


Vaping: Inhaling the aerosol or vapour from an electronic cigarette, e-vaporizer, or other device.

Ventral striatum: An area of the brain that is part of the basal ganglia and includes the nucleus accumbens; dopamine is released here in the presence of salient stimuli and in response to physically rewarding activities such as eating, sex, and taking drugs, and this process is a key factor behind the desire to repeat the behaviours associated with these rewarding activities.

Ventral tegmental area: An area in the brainstem that contains dopamine neurons that make up a key part of the brain reward system, which also includes the nucleus accumbens and prefrontal cortex.


Withdrawal: Symptoms that can occur after long-term use of a drug is reduced or stopped; these symptoms occur if tolerance to a substance has occurred, and vary according to substance. Withdrawal symptoms can include negative emotions such as stress, anxiety, or depression, as well as physical effects such as nausea, vomiting, muscle aches, and cramping, among others. Withdrawal symptoms often lead a person to use the substance again.

NIDA. Media Guide. National Institute on Drug Abuse website. July 2, 2018. Accessed January 16, 2020.



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