Glossary

The words you may hear from a doctor, therapist, or pharmacist, with a short, clear explanation of each and a trusted source behind every section.

Diagnosis and symptoms

Words you may hear when a provider evaluates mood changes. National Institute of Mental Health · Depression

Depression (major depressive disorder): A mood disorder that can cause severe symptoms affecting how a person feels, thinks, and handles daily activities such as sleeping, eating, or working. Diagnosis requires symptoms most of the day, nearly every day, for at least 2 weeks.
Depressed mood: Feeling sad, anxious, empty, or hopeless. In children and teens it may show up as irritability instead.
Loss of interest or pleasure: No longer enjoying hobbies, activities, or people that used to matter. One of the two core signs of depression.
Hypersomnia: Excessive sleepiness. More common in older children, teens, and young adults with depression.
Pseudodementia: Memory and thinking problems caused by severe depression, which can stand out in older adults.
Mania and hypomania: Periods of unusually high mood, energy, or irritability. Hypomania is less severe. They are part of bipolar disorder, not major depression.; National Institute of Mental Health · Bipolar disorder
Psychosis: Losing touch with reality, including delusions (false beliefs) and hallucinations (seeing or hearing things that are not there).; MedlinePlus · Major depression with psychotic features

Types of depression

Names for patterns of depression described on this site. Each type card links to its own source. National Institute of Mental Health · Depression

Major depressive disorder: Also called major depression or clinical depression. A low mood or loss of interest that lasts most of the day, nearly every day, for at least 2 weeks and gets in the way of daily life.
Persistent depressive disorder (dysthymia): Depression symptoms that are less severe than major depression but last much longer, usually at least 2 years. In children and teens the mood may be irritable and last at least 1 year.; MedlinePlus · Persistent depressive disorder
Perinatal and postpartum depression: Depression during pregnancy or in the weeks and months after childbirth. It is more than the "baby blues", which are mild and usually fade within about 2 weeks.; National Institute of Mental Health · Perinatal depression
Seasonal affective disorder (seasonal pattern): Depression that comes and goes with the seasons, most often starting in late fall or early winter and lifting in spring and summer. A less common summer pattern also exists.; National Institute of Mental Health · Seasonal affective disorder
Premenstrual dysphoric disorder (PMDD): A more severe form of premenstrual syndrome, with depression, irritability, and tension in the week before a period. Symptoms most often get better within a few days after the period starts.; MedlinePlus · Premenstrual dysphoric disorder
Perimenopausal depression: Depression that affects some women during the transition to menopause. Mood swings and poor sleep are common in this transition, but more extreme irritability, anxiety, sadness, or loss of enjoyment may be depression.; National Institute of Mental Health · Depression in women
Depression with symptoms of psychosis: Depression together with psychosis, a loss of contact with reality. A person may hear voices or hold false beliefs, often related to their depressed feelings.; MedlinePlus · Major depression with psychotic features
Bipolar depression (part of bipolar disorder): The low periods of bipolar disorder, which also brings manic or hypomanic periods of unusually high energy, mood, or irritability. It is a different condition from major depression.; National Institute of Mental Health · Bipolar disorder
Treatment-resistant depression: Depression that has not improved after trying at least two antidepressants. It is not a dead end: other medicines, add-on medicines, and brain stimulation therapies are options.
Depression in older adults: Common but not a normal part of aging. Sadness may not be the main sign; some older adults feel emotionally numb, lose interest in activities, or are less open to talking about feelings.; National Institute on Aging · Depression and older adults
Depression in children and teens: Children and teens may be irritable rather than sad. Younger children may be anxious or cranky, pretend to be sick, or refuse to go to school; older children and teens may sulk, get into trouble at school, or be easily frustrated.
Disruptive mood dysregulation disorder (DMDD): A mood disorder in children and teens with ongoing irritability and anger and frequent, intense temper outbursts. Symptoms are severe, show up in more than one setting, and affect daily life.; National Institute of Mental Health · Disruptive mood dysregulation disorder
Depression linked to substances or another illness: Depression tied to alcohol, medicines, or withdrawal, or to a separate illness such as heart disease or multiple sclerosis.; National Institute on Aging · Depression and older adults

Medicines

Short explanations of the medicine terms used on the Treatments page. National Institute of Mental Health · Mental health medications

Antidepressant: A medicine that treats depression by changing how the brain produces or uses certain chemicals involved in mood or stress. Usually takes 4-8 weeks to work.; National Institute of Mental Health · Depression
SSRI, SNRI, and NDRI: The most commonly prescribed antidepressant groups: selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and norepinephrine-dopamine reuptake inhibitors (NDRIs).
Tricyclics and MAOIs: Tricyclic antidepressants and monoamine oxidase inhibitors (MAOIs): older antidepressants with more side effects that may still be the best option for some people.
Treatment-resistant depression: Depression that does not improve after trying at least two antidepressants.; National Institute of Mental Health · Depression
Esketamine: A nasal spray approved by the U.S. Food and Drug Administration (FDA) for treatment-resistant depression, given in a health care setting. It often acts within a couple of hours.; National Institute of Mental Health · Depression
Serotonin syndrome: A rare but life-threatening reaction when medicines or supplements that act on serotonin are combined, such as antidepressants with triptans or St. John's wort. Signs include agitation, muscle twitches, hallucinations, and high temperature.
Boxed warning: A prominent warning near the top of a U.S. prescription label. Antidepressant labels carry one about suicidal thoughts and behaviors in children, teens, and young adults.; DailyMed · Prozac label
Add-on (adjunctive) treatment: A medicine taken together with an antidepressant to make treatment work better, such as an antipsychotic.; National Institute of Mental Health · Depression
Risk Evaluation and Mitigation Strategy (REMS): A drug safety program the FDA can require for certain medicines with serious safety concerns, to help make sure the benefits outweigh the risks. Esketamine (Spravato) is only available through one and must be given in a certified health care setting.; U.S. Food and Drug Administration · Risk Evaluation and Mitigation Strategies (REMS)

Therapy and brain stimulation

Non-medicine treatments and the words used to describe them. National Institute of Mental Health · Brain stimulation therapies

Psychotherapy (talk therapy): Treatments that help a person identify and change troubling emotions, thoughts, and behaviors, one-on-one or in a group, in person or virtually.; National Institute of Mental Health · Depression
Cognitive behavioral therapy (CBT): A therapy that helps people notice and challenge unhelpful thoughts and change behaviors to improve mood.; National Institute of Mental Health · Depression
Interpersonal therapy (IPT): A therapy focused on relationships and life events that affect mood.; National Institute of Mental Health · Depression
Safety plan: A written plan made with a therapist to recognize warning signs of self-harm or suicide and list coping steps and people to contact.; National Institute of Mental Health · Psychotherapies
Electroconvulsive therapy (ECT): A procedure under anesthesia that uses a brief electric current to cause seizure activity in the brain. Used for severe or treatment-resistant depression.
Repetitive transcranial magnetic stimulation (rTMS): Magnetic pulses aimed at a mood-related brain area, done awake without anesthesia.
Vagus nerve stimulation (VNS): An implanted device that stimulates the vagus nerve, approved for some long-lasting, hard-to-treat depression.
FDA approved vs FDA cleared: Two terms the U.S. Food and Drug Administration (FDA) uses for devices: approved means benefits were shown to outweigh known risks in clinical testing; cleared means the device is substantially equivalent to one already on the market.
Light therapy: Daily time in front of a very bright (10,000 lux) light box, used for winter-pattern seasonal depression.; National Institute of Mental Health · Seasonal affective disorder

Pregnancy and life stages

Terms for depression tied to specific times of life. National Institute of Mental Health · Perinatal depression

Baby blues: Mild, short-lasting mood changes, worry, and exhaustion that many new mothers have in the first 2 weeks after birth.
Perinatal depression: Depression during pregnancy (prenatal) or after childbirth (postpartum). Most episodes begin within 4-8 weeks after birth.
Postpartum psychosis: A rare, serious illness after childbirth with delusions, hallucinations, mania, paranoia, or confusion. It is a psychiatric emergency.