brain fog
noun
: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly
Examples of brain fog in a Sentence
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Brain Fog Some people report confusion and difficulty concentrating (also known as brain fog) when first starting the keto diet.
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Brittany Lubeck, Verywell Health, 28 Nov. 2025
Because the consequences tend to creep in gradually — brain fog, irritability, dependence — users often miss when therapeutic use shifts into compulsion.
—Leah Willingham, Fortune, 25 Nov. 2025
Symptoms can include fatigue, brain fog, dizziness, nausea, IBS, and chronic pain.
—Kara Nesvig, Parents, 20 Nov. 2025
With the latest range of supplements, Midi Health is hitting on several of the key concerns women experience during perimenopause and menopause, including brain fog, muscle loss and weight gain.
—Emily Burns, Footwear News, 18 Nov. 2025
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Brittany Lubeck, Verywell Health, 28 Nov. 2025
Because the consequences tend to creep in gradually — brain fog, irritability, dependence — users often miss when therapeutic use shifts into compulsion.
—Leah Willingham, Fortune, 25 Nov. 2025
Symptoms can include fatigue, brain fog, dizziness, nausea, IBS, and chronic pain.
—Kara Nesvig, Parents, 20 Nov. 2025
With the latest range of supplements, Midi Health is hitting on several of the key concerns women experience during perimenopause and menopause, including brain fog, muscle loss and weight gain.
—Emily Burns, Footwear News, 18 Nov. 2025
See All Example Sentences for brain fog
Cite this Entry
“Brain fog.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/brain%20fog. Accessed 30 Nov. 2025.
Copy CitationMedical Definition
brain fog
noun
: a usually temporary state of diminished mental capacity marked by inability to concentrate or to think or reason clearly
This brain fog can be a result of being overly stressed, tired, carrying extra weight, consuming too many calories or consistently consuming a diet poor in nutrients.—Kylie Helgens, The Gazette (Cedar Rapids, Iowa)
Kylie Helgens, The Gazette (Cedar Rapids, Iowa)Love words? Need even more definitions?
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