major depressive disorder

noun

: a serious mood disorder involving one or more episodes of intense psychological depression or loss of interest or pleasure that lasts two or more weeks and is accompanied by irritability, fatigue, poor concentration, sleep disturbances, weight gain or loss, feelings of worthlessness or guilt, and sometimes suicidal tendencies : clinical depression, major depression

About 18 million Americans are diagnosed with a major depressive disorder each year.

—David Schwab

The most serious form of depression is major depressive disorder, characterized by depressed mood, loss of interest or pleasure, changes in appetite, increased or decreased sleep, increased or decreased motor activity, fatigue, feelings of worthlessness or guilt, difficulty concentrating and, for some people, recurrent thoughts of death or suicide.

—Sandi Lloyd

—abbreviation MDD

Examples of major depressive disorder in a Sentence

Recent Examples on the Web

Researchers are working hard to find non-invasive, drug-free ways to treat conditions such as ADHD and major depressive disorder (MDD), and there have been a lot of promising studies on experimental therapies. —New Atlas, 21 Jan. 2026

It is designed for adults 18 and older with moderate to severe major depressive disorder. —Kurt Knutsson, FOXNews.com, 20 Jan. 2026

Zeko’s predicament fit what experts call treatment-resistant depression, which isn’t a formal diagnosis separate from major depressive disorder. —Cnn.com Wire Service, Mercury News, 15 Jan. 2026

Antipsychotics Antipsychotics are medications used to treat serious mental health conditions like major depressive disorder and schizophrenia. —Carrie Madormo, Verywell Health, 7 Jan. 2026

Word History

First Known Use

1975, in the meaning defined above

Rhymes for major depressive disorder

• boarder
• border
• corder
• order
• warder
• camcorder
• recorder
• reorder
• suborder
• transborder

Medical Definition

major depressive disorder

noun

: a serious mood disorder involving one or more episodes of intense psychological depression or loss of interest or pleasure that lasts two or more weeks and is accompanied by irritability, fatigue, poor concentration, sleep disturbances, weight gain or loss, feelings of worthlessness or guilt, and sometimes suicidal tendencies : clinical depression, major depression

The diagnosis of both major depressive disorder and subsyndromal symptoms is complicated by difficulties that elderly patients may have in recognizing or describing depressive symptoms.

—Lawrence M. Martin et al., The John Hopkins White Papers

—abbreviation MDD