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
David SchwabThe 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
Sandi LloydExamples of major depressive disorder in a Sentence
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One of our children still lives with me and has been diagnosed with autism, ADHD, PTSD and major depressive disorder.
—Jeanne Phillips, Mercury News, 10 Feb. 2026
One of them still lives at home and has been diagnosed with autism, ADHD, PTSD and major depressive disorder.
—Jeanne Phillips, Dallas Morning News, 10 Feb. 2026
Some research suggests that omega-3 supplements may improve mood for people with major depressive disorder.
—Sarah Garone, Health, 30 Jan. 2026
The initiative, dubbed the Party Line project, is the brainchild of Matter Neuroscience, a mental health startup focused on researching the science behind happiness and creating tools to battle major depressive disorders.
—Clara Harter, Los Angeles Times, 23 Jan. 2026
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Jeanne Phillips, Mercury News, 10 Feb. 2026
One of them still lives at home and has been diagnosed with autism, ADHD, PTSD and major depressive disorder.
—Jeanne Phillips, Dallas Morning News, 10 Feb. 2026
Some research suggests that omega-3 supplements may improve mood for people with major depressive disorder.
—Sarah Garone, Health, 30 Jan. 2026
The initiative, dubbed the Party Line project, is the brainchild of Matter Neuroscience, a mental health startup focused on researching the science behind happiness and creating tools to battle major depressive disorders.
—Clara Harter, Los Angeles Times, 23 Jan. 2026
See All Example Sentences for major depressive disorder
Cite this Entry
“Major depressive disorder.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/major%20depressive%20disorder. Accessed 14 Feb. 2026.
Copy CitationMedical 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
Lawrence M. Martin et al., The John Hopkins White PapersLove words? Need even more definitions?
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