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

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Physicians told them to tough out the joint pain and brain fog that comes with menopause. — Laura Trujillo, USA Today, 30 June 2026 Persistent fatigue despite adequate sleep, dizziness, breathlessness, brain fog, low mood, brittle nails, hair fall, feeling unusually cold, and changes in skin quality all signal low ferritin levels. — Tatiana Dias, Vogue, 30 June 2026 My medication has resolved or significantly improved my symptoms, including the body rash, itching, fatigue, brain fog, and joint and muscle pain. — Kelly Morlan, Health, 30 June 2026 Those included headaches, insomnia, light and noise sensitivity, brain fog, anxiety, confusion, joint pain, disordered eating, nausea and weight loss and gain. — Emily Blackwood, PEOPLE, 30 June 2026 See All Example Sentences for brain fog

Word History

First Known Use

1853, in the meaning defined above

Time Traveler
The first known use of brain fog was in 1853

Rhymes for brain fog

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Browse Nearby Words

brain-fever bird
brain fog
brain freeze
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Cite this Entry

“Brain fog.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/brain%20fog. Accessed 10 Jul. 2026.

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Medical 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)
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